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Research & Statistics Board Review DH227 Lisa Mayo, RDH, BSDH Concorde Career College

Lisa Mayo, RDH, BSDH Concorde Career College. Continued search for truth using the scientific method Systematic, objective laboratory, field and clinical

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Page 1: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Research & Statistics Board Review DH227

Lisa Mayo, RDH, BSDHConcorde Career College

Page 2: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Continued search for truth using the scientific method

Systematic, objective laboratory, field and clinical investigations that lead to improvement of oral diseases and health care delivery

What is Research?

Page 3: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Methods used in any type of rsrch that increase the likelihood that info gathered will be relevant, reliable and unbiased

Steps include◦ Identification & statement of the problem◦ Formulation of a hypothesis◦ Collection, organization, analysis of data◦ Formulation of conclusions◦ Verification, rejection, modification of hypothesis

What is Scientific Method?

Page 4: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Identify problem Develop the hypothesis or research

questions Design the research plan Data collection – implementation Data analysis and interpretation Conclusions

Steps in the Research Process

Page 5: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Independent Variable◦ Manipulated variable to produce a response to the

dependent variable◦ Presumed cause

Dependent Variable◦ Shows effects of change, provides measurement data◦ Presumed effect◦ The DEPENDent variable DEPENDs on the

independent variable Example

◦ Independent = study grps vs independent studying◦ Dependent = graduation rates

Terminology

Page 6: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

The following is correct of Dependent Variable:

a. Allows us to generalize from the sample of data to a larger group of subjects

b. Concerned with presentation, organization, and summarization of the data

c. The outcome of interest; should change in response to some intervention

d. The intervention, what is being manipulatede. Each element in the population has equal

chances of appearing: reduces the chance of bias

NBQ

Page 7: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

The following is correct of Dependent Variable:

a. Allows us to generalize from the sample of data to a larger group of subjects

b. Concerned with presentation, organization, and summarization of the data

c. The outcome of interest; should change in response to some intervention

d. The intervention, what is being manipulatede. Each element in the population has equal

chances of appearing: reduces the chance of bias

NBQ

Page 8: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

The variable controlled or manipulated in a study is

a. Population parameterb. Dependent variablec. Independent variabled. Variablee. Discrete number

NBQ

Page 9: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

The variable controlled or manipulated in a study is

a. Population parameterb. Dependent variablec. Independent variabled. Variablee. Discrete number

NBQ

Page 10: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Extraneous Variable◦ Not germane to study, attempts are made to

control them or build them into the study Study Groups

◦ Control/experimental (2nd grp to compare) Sample

◦ Portion of population chosen to be studied in order to gain information about the entire population

Terminology

Page 11: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Reliability◦ Consistency of measurement, repeatability◦ The extent to which the method of measurement performs

consistently Single Blind

◦ When either subjects or raters, but not both, are unaware of subject placement into experimental grps

Double Blind◦ When both raters and subjects are unaware of which

treatment subject is receiving Validity

◦ The extent to which a scoring procedure measures that it was designed to measure

◦ Every step should be taken to maximize validity in a study

Terminology

Page 12: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Predictive Value (Sensitivity & Specificity)◦ Ability of a diagnostic test to accurately measure both

the presence and absence of disease Rate

◦ Numeric expression of disease in a population in which the # of the disease occurrence appears as the numerator and # possible occurrences appears as the denominator

◦ Usually includes a time dimension (year, months…)◦ Allows for valid comparisons from one year to the next◦ Ex: # of newborn deaths w/in first year of life per 1000

births ◦ Ex: % of people diagnosed w/oral cancer last year

Terminology

Page 13: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

The extent to which the method of measurement performs consistently

A. RangeB. Standard DeviationC. ValidityD. ReliabilityE. ANOVA

NBQ

Page 14: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

The extent to which the method of measurement performs consistently

A. RangeB. Standard DeviationC. ValidityD. ReliabilityE. ANOVA

NBQ

Page 15: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Radom Sample◦ Sample of subjects having equal & independent

chances of being selected◦ Pick names out of a hat

Stratified Sample◦ Subjects randomly chosen from a previously

subdivided population (diabetes vs no diabetes)◦ Divide class into 2 groups then select 2 members

from each group to participate Non-Random Sample

◦ One where bias enters in choice of participants

Research Samples

Page 16: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Systematic sample◦ Select every “nth” person to participate

Judgment Sample◦ Some familiar with the population selects the

sample◦ HIGH chance of bias!!

Convenience Sample◦ Group chose based solely on convenience◦ First 10 people to walk through door fill out

questionnaire

Research Samples

Page 17: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Descriptive Studies◦ Designed the describe the extent of a disease or

condition within a population and its relationship with other variables

◦ Determines who is getting the disease and where and when the disease is occurring

Experimental Studies◦ Tests hypotheses to establish CAUSE◦ Carried out under controlled situations◦ Uses control groups and tx groups

Analytical Studies◦ Aimed at formulating a hypothesis◦ Three main points: Retrospective, Prospective,

Longitudinal

Research Methods

Page 18: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Standard Deviation◦ Most commonly used method of dispersion in hyg rsrch

Formative Evaluation◦ Internal eval during early implementation

Summative Evaluation◦ Judges the merit of the program after it has been in

operation Descriptive Statistics

◦ Describes and summarizes a set of data numerically Inferential Statistics

◦ Generalize about the probable results of a large group when only a select portion of the grp has been observed

Eval & Rsrch

Page 19: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Evidence-based practice◦Using most current evidence to make

decisions about the care of individual patients

◦Evidence alone not sufficient to make decisions

◦Evidence ranking important See next slide

Epidemiology & Research

Page 20: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

PYRAMID of EVIDENCE

Systematic Review & Meta-Analysis -“Gold Standard” Highest level clinical evidence -Synthesis of 2 or more randomized controlled trials answering the same question

As go up pyramid

Not all levels are equally useful for making patient care decisions

# studies decrease

relevance to answering clinical questions increase

Page 21: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Categories of community health rsrch◦ Epidemiologic rsrch to determine the presence

and distribution of disease in the population and factors that relate to the occurrence of disease within the population

◦ Clinical trials and tests of techniques and products to prevent and control disease

◦ Rsrch in educational techniques and the behavioral sciences related to oral health education

◦ Eval of community oral hl programs

Epidemiology & Research

Page 22: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Risk versus causality◦Risk identifies attributes that are assoc w/a

disease Case-control and cohort studies

◦Causality identifies factors that have been demonstrated to be causally related Randomized controlled clinical trials

◦Risk is established w/analytic studies◦Causality is established with experimental

studies

Epidemiology & Research

Page 23: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Risk versus causality: Types of risk attributesRisk factors

Strong identification of risk, causality is inferredCan be modified Important in making recommendations to patients

Risk indicatorsWeaker indication of riskCausality may be incorrectly assumedCan be modifiedShould be applied w/care in recommendations

Risk Predictors/Risk Marker/Demographic Risk FactorNon-modifiableHas no role in making recommendations to patient but

has importance in identifying target populations for community health programs

Epidemiology & Research

Page 24: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

3 classifications of epidemiological rsrch1. Descriptive

Involves description, analysis, interpretation of data to eval a current event or situation

Does NOT test a hypothesis but helps increase understanding of a disease

Uses survey method with a cross-sectional design

2. Analytic3. Experimental

Epidemiology & Research

Page 25: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

3 classifications of epidemiological rsrch2. Analytic

Observation of a disease or condition to id what causes disease

Does not establish causality – just observes Also called Observational or Development studies Non-interventional Purpose: help formulate a HYPOTHESIS for

experimental studies 3 Types

1. Cohort2. Case-Control3. Cross-Sectional

Epidemiology & Research

Page 26: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Epidemiology & Research

Analytic Research

Groups used

Cohort Uses defined grp

ProspectiveLongitudinal

Establishes incidence

Confirms risk factors

Case-Control Compares 2 grps (case & controls – those with & w/out disease

Retrospective (too many ethical compromises to use prospective)

Cross-Sectional

One grp & several sub-grps

Establishes prevalence

Cannot confirm risk factors

Page 27: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

3 classifications of epidemiological rsrch3. Experimental

Test a hypothesis after analytic studies have inferred the cause of the disease

Deliberate manipulation of the supposed cause or controlling agent of a condition & observation of the result (longitudinal)

Establishes causality A randomized clinical trial is a well-controlled

experimental study with humans Experimental study that is not well controlled is

called quasi-experimental

Epidemiology & Research

Page 28: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

3 classifications of epidemiological rsrch3. Experimental: Requirements

Use a control grpControl extraneous variablesRandomizationControl of errors in measurement (↑ validity &

reliability)Independent variable is manipulatedDependent variable is measured

Epidemiology & Research

Page 29: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

3 classifications of epidemiological rsrch3. Experimental

Representative sample is required to allow for generalizations (also called inference)

If use small convenience samples: Replication studies are needed due to low external validity Repeated studies w/different samples

Multiple-site studies broaden the representation of the population = improve validity

Epidemiology & Research

Page 30: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

3 classifications of epidemiological rsrch3. Experimental Study designs

1. Pre-test/Post-Test2. Post-Test Only3. Split mouth4. Cross-Over5. Time-Series (Repeated Measures)6. Blind (Making)7. Designs can be combined

Epidemiology & Research

Page 31: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

3 classifications of epidemiological rsrch3. Experimental Study designs

1. Pretest/Post-Test Dependent variable is measured before &

after introducing the independent variable Provides a baseline measure for comparison

2. Post-Test Only Dependent variable is measured only after

introducing the independent variable Controls any possible effect of the pretest

procedure on the dependent variable3. Split mouth

Procedure unique to oral hl rsrch Side of mouth receives different interventions Controls subject-related variables

Epidemiology & Research

Page 32: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

3 classifications of epidemiological rsrch3. Experimental Study designs

4. Cross-Over Ea grp receives a different intervention or

control & after a period, they are switched over the opposite tx

Controls subject-related variables5. Time-Series (Repeated Measures)

Dependent variable is measured several times over a specific period to determine whether its effect on the dependent variable holds over time

6. Blind (Making) Examiners measuring the dependent variable

w/out knowing the grp assignment Eliminates bias

Epidemiology & Research

Page 33: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

A cross-over design research project includes what type of period:

A. Time seriesB. RandomC. WashoutD. PlaceboE. Both A and D

NBQ

Page 34: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

A cross-over design research project includes what type of period:

A. Time seriesB. RandomC. WashoutD. PlaceboE. Both A and D

NBQ

Page 35: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Research always begins with a(n) _______ A) Trend B) QuestionC) Answer D) Survey E) All of the above

NBQ

Page 36: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Research always begins with a(n) _______ A) Trend B) QuestionC) Answer D) Survey E) All of the above

NBQ

Page 37: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Hypothesis◦ Predictive statement of the expected outcome or

relationship among variables◦ Answers rsrch questions in a manner that is

observable and measurable

http://www.youtube.com/watch?v=onVxp40MisI

Epidemiology & Research

Page 38: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Hypothesis◦ Null hypothesis

Negative statement of the hypothesis that assumes the absence of statistically significant differences between the sample grps

Ex: statement that no difference exists in the effectiveness of the 2 treatments

◦ Rsrch Hypothesis/Positive/Alternative Positive statement of the hypothesis is in terms that

express the opinion or prediction of the researcher Ex: statement that a difference exists in the

effectiveness of the 2 tx’s

Epidemiology & Research

Page 39: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Sampling◦ Random Sample

Increases external validity by controlling differences in study participants which allows for valid generalization of results to the population

Reduced bias in research

Epidemiology & Research

Page 40: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Sampling◦ Stratified Random Sample

Participants randomly chosen from an existing, know subdivided population

Results in the sample proportionately and accurately representing the subgrps in the population

Epidemiology & Research

Page 41: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Sampling◦ Systematic Random Sample

Selection of every nth member of the population from a list of the total population

The n depends on the size of the sample desired in relation to the population

Ex: 10% is every tenth member of the population Not a strictly random sample

Epidemiology & Research

Page 42: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Sampling◦ Convenience Sample

Study participants chosen on the basis of availability Used when access to the total population is not

feasible Bias is likely = reduces validity of sample and limits

the generalizability of study results

Epidemiology & Research

Page 43: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Sampling◦ Judgment or Purposive Sample

Study participants chosen by researcher or someone who has knowledge of the population

Biased Least valid method Generalization of results not possible

Epidemiology & Research

Page 44: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Sampling◦ Table of random numbers

Table composed of numbers that have been generated by a random technique used to select a random sample

Done by computers

Epidemiology & Research

Page 45: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Sampling◦ Sample Size: which one increases reliability of

results? Large sample

Accurately represents the defined population Increases precision, accuracy data collected Reduced standard error of sample mean Required for descriptive rsrch

Small sample May be necessary, depending on the purpose of the rsrch May lead to inaccurate conclusion when inappropriate for

the type of rsrch Require specialized statistics

Epidemiology & Research

Page 46: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Sampling◦ Grp Assignment

Assignment of participants to the grps of the study

Experimental Grp: receives independent variable

Control Grp: Does NOT receive experimental tx (independent variable)

Epidemiology & Research

Page 47: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

To determine attitudes toward a fluoride mouthrinse program initiated in the local school system, a hygienist distributes a questionnaire to a group of parents. All of the following are likely limitations of this survey except:a. Incomplete responses by parentsb. Significant cost for conducting the researchc. Misinterpretation of questions by parentsd. Parents responding in the manner in which they think the hygienist wants them to respond

Question

Page 48: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

To determine attitudes toward a fluoride mouthrinse program initiated in the local school system, a hygienist distributes a questionnaire to a group of parents. All of the following are likely limitations of this survey except:a. Incomplete responses by parentsb. Significant cost for conducting the researchc. Misinterpretation of questions by parentsd. Parents responding in the manner in which they think the hygienist wants them to respond

Answer

Page 49: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Science that describes, summarizes, analyzes and interprets numerical data for the purpose of making an inference about a population

Statistic: numerical character of a sample derived from the data collect

Parameter: numerical characteristic of a population

Statistics

Page 50: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

1. Descriptive statistics/Inferential: statistics used to numerically describe & summarize data collected Mean, median, mode Measures of dispersion: range, variance, standard

deviation

2. Correlation Statistics: statistical measure for determining the strength of the linear relationship between 2 or more variables Graph curves: negative, positive skew

Statistics

Page 51: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

3. Inferential Statistics Used to infer rsrch findings from the

sample to the general population from which the sample was taken

Used to test hypothesis, generalize results to a larger population of interest, provide evidence of causality

Statistics

Page 52: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

1. Frequency distribution: scores arranged in order and by how often they occur

2. Scales of Measurement: nominal (name) ordinal (rank order)interval (equal intervals) ratio (all the above plus a true 0 point)

3. Graphing Techniques: X&Y4. Measurements of Central Tendency mean:

average median: midpoint mode: most frequently occurring score

5. Terms of Dispersion or Variabilityrange: difference between high and low scoresstandard deviation: dispersion around the mean (smaller sd = more homogeneous the grp)

1. Descriptive statistics

Page 53: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

The most commonly used method of dispersion in oral hygiene research:

A. RangeB. Standard DeviationC. ValidityD. ReliabilityE. ANOVA

NBQ

Page 54: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

The most commonly used method of dispersion in oral hygiene research:

A. RangeB. Standard DeviationC. ValidityD. ReliabilityE. ANOVA

NBQ

Page 55: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

The arithmetic average of scores Most common measure of central tendency

Mean

Page 56: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Divides the distribution of scores into 2 equal parts

50% of the scores will be above and 50% will be below

NOT affected by extreme high or low scores

Median

Page 57: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

The MOST frequently occurring score within the data matrix

Affects the skew of the graph

Mode

Page 58: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

The gingival index (GI) scores of residents in the dementia wing were: 2,5, 2.75, 2.8, 3.0, 2.5, 2.0, 2.4, and 2.9. Which of the following represents the mean GI score?

a. 2.50b. 2.55c. 2.61d. 2.63e. 2.75

Question

Page 59: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

The gingival index (GI) scores of residents in the dementia wing were: 2,5, 2.75, 2.8, 3.0, 2.5, 2.0, 2.4, and 2.9. Which of the following represents the mean GI score?

a. 2.50b. 2.55c. 2.61d. 2.63e. 2.75

Answer

Page 60: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

The value that occurs with the greatest frequency:

A. MeanB. MedianC. ModeD. Positive SkewE. Negative Skew

NBQ

Page 61: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

The value that occurs with the greatest frequency:

A. MeanB. MedianC. ModeD. Positive SkewE. Negative Skew

NBQ

Page 62: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

The most common measure of central tendency: A. Mean

B. MedianC. ModeD. Positive SkewE. Negative Skew

NBQ

Page 63: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

The most common measure of central tendency: A. Mean

B. MedianC. ModeD. Positive SkewE. Negative Skew

NBQ

Page 64: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

When data is plotted using a normal (BELL) curve, the mean, median, and mode are EQUAL!

Board Alert!

Page 65: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Described how WIDE the scores are around a central point

Normal curve, central point would be the mean/median/mode

Range/Domain◦ Difference between the high and low score of a data matrix◦ Affected by extremely high or low scores

Standard Deviation◦ Represents the square root of the sample variance◦ SD is the MOST commonly used method of dispersion in oral

hygiene rsrch and reflects the range within the data matrix◦ Bigger the range or SD = wider distribution curve

Measures of Dispersion

Page 66: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Depends on 2 factors:◦ Mean ◦ Standard deviation

Mean identifies the position of the center Standard deviation determines the height

and width of the bell◦ Example: large standard deviation creates a bell

that is short and wide while a small standard deviation creates a tall and narrow curve

Bell Curves

Page 67: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

• About 68% of the area under the curve falls within 1 standard deviation

•About 95% of the area under the curve falls within 2 standard deviations

•About 99.7% of the area under the curve falls within 3 standard deviations.

Bell Curves Rules

Page 68: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Mean, Median, Mode, SD

Page 69: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical
Page 70: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

What is the most common measure of dispersion?

a. Meanb. Rangec. Data matrixd. Standard deviation

Question

Page 71: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

What is the most common measure of dispersion?

a. Meanb. Rangec. Data matrixd. Standard deviation

Question

Page 72: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Ranking students from the individual with the highest GPA to the lowest is an example of a(an):a. Ordinal scaleb. Nominal scalec. Interval scaled. Ratio scalee. Count

Question

Page 73: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Ranking students from the individual with the highest GPA to the lowest is an example of a(an):a. Ordinal scaleb. Nominal scalec. Interval scaled. Ratio scalee. Count

Answer

Page 74: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Ex of narrow and wide distribution curvesWhich one has the greatest range or SD?

Page 75: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Ex of narrow and wide distribution curvesWhich one has the greatest range/SD?Range: Difference between the high and low score of a data matrix. Affected by extremely high or low scores

Page 76: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Notice that majority of scores fall between +1 and -1 SD when plotted on a Bell curve – ABOSLUTE!

BOARD ALERT!!

Page 77: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Most events in this world tend to fall into a bell-shaped curve called a normal distribution, sometimes called the _______

A. Left skewB. Positive skewC. Gaussian distributionD. Right skewE. None of the above

NBQ

Page 78: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Most events in this world tend to fall into a bell-shaped curve called a normal distribution, sometimes called the _______

A. Left skewB. Positive skewC. Gaussian distributionD. Right skewE. None of the above

NBQ

Page 79: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

When graphed data asymmetrical appearance (not a Bell), it is said to be SKEWED

Positive Skew◦ When more scores fall into lower range◦ The right tail is longer; the mass of the

distribution is concentrated on the left of the figure. The distribution is said to be right-skewed, right-tailed, or skewed to the right

Negative Skew◦ When more scores fall into the higher range◦ The left tail is longer; the mass of the

distribution is concentrated on the right of the figure. The distribution is said to be left-skewed, left-tailed, or skewed to the left

2. Correlation Statistics Graph Curves

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More scores are in the lower range with a few scores in the higher range: A. Mean

B. MedianC. ModeD. Positive SkewE. Negative Skew

NBQ

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More scores are in the lower range with a few scores in the higher range: A. Mean

B. MedianC. ModeD. Positive SkewE. Negative Skew

NBQ

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All of the following are effects of grouping data in tables and graphs except:a. Loss of detailb. Easier calculationc. More concise presentationd. Clearer identification of trendse. Specific detailed information

Question

Page 85: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

All of the following are effects of grouping data in tables and graphs except:a. Loss of detailb. Easier calculationc. More concise presentationd. Clearer identification of trendse. Specific detailed information

Answer

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Sample selected to generalize (infer) about the population at large

Parametric statistics◦ Population value defined by the statistics◦ Normally use a Bell Curve as data analysis◦ Large, random sample

Nonparametric statistics◦ Population parameters do not meet the assumption

required for parametric statistics◦ Data are nominal or ordinal in nature◦ Population from which the sample is drawn does not

have a normal distribution (skewed)◦ May or may not be a small sample

3. Inferential Statistics

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Tests of Significance1. P Value2. T-test3. Correlation4. ANOVA5. F-test6. Chi-Square Test

3. Inferential Statistics

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Reliability: the extent to which the method of measurement consistently performs. 2 types of examiner reliability1. Intrarater/Intraexaminer

Reliability indicated by same examiner is scoring equivalently time and time again.

Consistency of a single examiner in the application of an index or instrument over time to measure a disease/condition

2. Interater/Interexaminer Reliability indicates that consistency exists between

different examiners. Increased by calibration. Agreement among 2 or more examiners as they apply an

index or instrument over time to measure a disease or conditions

Inferential Statistics

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Intrarater

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Interrater

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Sensitivity◦ Ability of a test to correctly id the PRESENCE of a disease

Specificity◦ Ability of a test to show the ABSENCE of a disease

Correlation Co-Efficient◦ Determine strength of relationship between 2 variables◦ Shows probable cause and effect◦ Given as a # between +1 and -1(Board Alert: the closer

the correlation co-efficient is to EITHER +1 or -1, the STRONGER the correlation!)

◦ Positive Correlation = as the value of x ↑, the value of y ↑◦ Negative Correlation = as the value of x ↑, the value of

y↓

Inferential Statistics

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A study with high interrater reliability is a study in which:a. Results were not due to chanceb. One observer viewed the subjects the same way each timec. Two or more observers viewed the subjects the same wayd. The factor measures is the factor intended

to be measurede. Results are generalized to the population

from which subjects were drawn

Question

Page 93: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

A study with high interrater reliability is a study in which:a. Results were not due to chanceb. One observer viewed the subjects the same way each timec. Two or more observers viewed the subjects the same wayd. The factor measures is the factor intended

to be measurede. Results are generalized to the population

from which subjects were drawn

Answer

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Probability: use when testing a hypothesis Tells researcher if findings are significant beyond the

possibility of chance Also known as statistical level/alpha value Small p: indicate rare chance occurrence, decision

probably correct Large p: indicate that chance occurrence more likely Maximum p value to reject null hypothesis

◦ Oral rsrch = 0.05 (BOARD ALERT!)◦ P= 0.01 and0.001 indicate greater statistical significance

P Value

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If significance is shown:◦ Experimental grp is different from control◦ Obtained difference is less likely to be a chance of occurrence

and is more likely due to the effects of the independent variable

◦ P=0.05 Observed diff. could be expected to occur by chance

◦ P > 0.05 Results r probably due to chance

◦ P < 0.05 statistically significant: 95% chance that what you found is due to

treatment, 5% chance what you found is due to error

P Value

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P=0.01 1 out of 100 significant P=0.001 1 out of a 1000 significant

P Value

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In statistical analysis, a p-value of 0.0001 denotes findings that are

a. Significantly differentb. Barely significantc. Very significantd. Very highly insignificante. Data are the same – no significance

NBQ

Page 98: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

In statistical analysis, a p-value of 0.0001 denotes findings that are

a. Significantly differentb. Barely significantc. Very significantd. Very highly insignificante. Data are the same – no significance

NBQ

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The proportion of those with true disease that is diagnosed with the new test as having the disease:

A. p-ValueB. Positive correlationC. Negative correlationD. SensitivityE. Specificity

NBQ

Page 100: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

The proportion of those with true disease that is diagnosed with the new test as having the disease:

A. p-ValueB. Positive correlationC. Negative correlationD. Sensitivity (PRESENCE OF DISEASE)E. Specificity

NBQ

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The ability of a diagnostic test to correctly identify the absence of disease:

A. p-ValueB. Positive correlationC. Negative correlationD. SensitivityE. Specificity (ABSENCE OF DISEASE)

NBQ

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The subjects score on one scale is a fairly good predictor of that person’s score on the other scale. As the value of x variable increases, the value of y increases:

A. p-ValueB. Positive correlationC. Negative correlationD. SensitivityE. Specificity

NBQ

Page 103: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

The subjects score on one scale is a fairly good predictor of that person’s score on the other scale. As the value of x variable increases, the value of y increases:

A. p-ValueB. Positive correlationC. Negative correlationD. SensitivityE. Specificity

NBQ

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Significance of the difference between 2 mean scores

The t-test assesses whether the means of two groups are statistically different from each other

Memory Tip = T stands for Two

T-Test

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Statistical measure for determining strength of the linear relationship between 2 variables◦ (+1) and (-1) are the strongest correlations

Positive Correlation: value of one increases so does the value of the other

Negative Correlation: value of one increases, the value of the other decreases

Correlation

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Analyze the effects of 2 or more independent variables simultaneously within the same rsrch design (Ex: pancreatic cancer risk in diabetic patients who also use tobacco)

Determines interactions among the variables in multiple sample grps

Used to analyze 3 or more mean scores

Analysis of Variance (ANOVA)

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The F-test is designed to test if 2 population variances are equal

Compares the ratio of two variances So, if the variances are equal, the ratio of

the variances will be 1 Parametric test

F-Test

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The F-distribution is found by:Ratio of 2 independent chi-square variables Respective degrees of freedom

Since F is formed by chi-square, many of the chi-square properties carry over to the F distribution ◦ The F-values are all non-negative ◦ The distribution is non-symmetric ◦ The mean is approximately 1 ◦ There are two independent degrees of freedom:

1for the numerator, and 1 for the denominator◦ There are many different F distributions, one for

each pair of degrees of freedom

F-Test

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Non-parametric test Used to determine if there is a statistical

difference between expected values and observed values

Chi-square is a statistical test commonly used to test a hypothesis◦ Chi-square is always testing the null hypothesis,

which states that there is no significant difference between the expected and observed result

Chi Square Test

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Abstract: condensed version of the purpose Introduction Methods & Materials: detailed description of

the research instruments, equipment, procedures, methods of data analysis

Results: summary of all relevant data Discussion: eval and interpret findings Conclusion: Summarize the main points you

made and recommendations and review hypothesis

Research Reports: Boart Alert!!

Page 114: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

To evaluate the statistical significance of the difference between 2 means when data meets parametric assumptions, one uses a _____, whereas to evaluate the expected values versus the observed values of 2 more samples when data meets nonparametric assumptions, one uses a ______. Which combination makes the statement correctly?

a. Chi-square test, t-testb. Chi square test, f-testc. t-Test, chi squared testd. t-test, f-teste. Correlation coefficient, chi square test

NBQ

Page 115: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

To evaluate the statistical significance of the difference between 2 means when data meets parametric assumptions, one uses a _____, whereas to evaluate the expected values versus the observed values of 2 more samples when data meets nonparametric assumptions, one uses a ______. Which combination makes the statement correct?

a. Chi-square test, t-testb. Chi square test, f-testc. t-Test, chi squared testd. t-test, f-teste. Correlation coefficient, chi square test

NBQ

Page 116: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Which of the following parts of a research report should evaluate and interpret findings?:

A. ResultsB. AbstractC. DiscussionD. ConclusionE. Literature review

NBQ

Page 117: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

Which of the following parts of a research report should evaluate and interpret findings?:

A. ResultsB. AbstractC. DiscussionD. ConclusionE. Literature review

NBQ

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What is a body of techniques that uses observation, reason, and experimentation to further evidence:

A. Science measurementB. Scientific methodC. Evidence-based methodD. Retroactive methodE. Both A and B

NBQ

Page 119: Lisa Mayo, RDH, BSDH Concorde Career College.  Continued search for truth using the scientific method  Systematic, objective laboratory, field and clinical

What is a body of techniques that uses observation, reason, and experimentation to further evidence:

A. Science measurementB. Scientific methodC. Evidence-based methodD. Retroactive methodE. Both A and B

NBQ