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CHAPTER 6 Psychological Research and Statistics

CHAPTER 6 Psychological Research and Statistics. Objectives Describe the process of psychological research Name the different types of psychological

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Page 1: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

CHAPTER 6

Psychological Research and Statistics

Page 2: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Objectives

Describe the process of psychological research

Name the different types of psychological research and some of the methodological hazards of doing research

Describe descriptive and inferential statistics

Name specific research methods used to organize data

Page 3: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Gathering Data

How do psychologists collect information about the topic they’ve chosen to study?

Page 4: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Gathering Data

Validity – extent to which an instrument measures or predicts what it is supposed to

Algebra questions would not be a valid measure of what you learned in Psych class

Page 5: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Gathering Data

Sample – relatively small group out of the total population

Population – an entire group as a whole Sample must be representative of the

population If a sample is not representative, then it

is biasedHow can researchers avoid bias?

Page 6: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Gathering Data

What does correlation mean? The degree of relatedness between

two sets of data

Two types - positive correlation & negative correlation

Page 7: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Gathering Data

IQ scores and academic success – positive correlation (direct relationship) The higher your IQ, the higher your

grades

Car speed and time it takes to travel somewhere – negative correlation (inverse relationship)

- as car speed increases, time it takes to reach your destination decreases

Page 8: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Correlations

Your turn!

Hours in the sun and chance of sunburn Positive correlation

Amount of exercise and % body fatNegative correlation

Mrs. Bird’s high school GPA and your high school GPAno correlation

Page 9: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Correlations

A researcher uses statistics to compute their research findings Statistics = field of mathematics that

involves the analysis of numerical data about representative sample of population

Correlation coefficient = needs to be near 1 (-/+), the closer results

are to -1 or +1 the better the relatability between the two variables

Page 10: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Experiments

Why do researchers choose experimentation over other research methods? Researchers can control the situation. Can establish cause and effect, only

research method in which you can

The goal of research is to prove or disprove a . . .Hypothesis

Page 11: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Experiments

Variables – conditions and behaviors that are subject to variation/change

Two types of variables – independent and dependent IV – manipulated variable in order to

view its effects DV – dependent upon the IV – affected

by it, the one the researcher measures

Page 12: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Experiments

Experimental group – consists of subjects who undergo the experimental treatment – variables are applied to this group

Control group – consists of subjects who do not receive experimental treatment Why is this group necessary?

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Experiments in Psych

Avoid Researcher Bias: researcher’s desire to prove hypothesis affects results

Avoid Self-fulfilling prophecy: researcher’s desire to prove hypothesis affects results

Could be very subtle or unconscious, but researcher will treat one group slightly differenty (body language, tone of voice)

Page 14: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Avoiding Researcher Bias

Use double-blind = neither researcher nor subjects know what group they are in, helps reduce researcher influencing results

Confounding variables = factors that cause changes in the dependent variable that aren’t the independent variables

Page 15: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Quasi-Experiment (“sort of” experiment)

For example, imagine that we wanted to do a study to compare student performance. Imagine further that we scheduled two sections of the course, let students sign up for which one they wanted, and then taught one using cooperative learning and the other using standard lecture.  Note that this study includes a manipulated independent variable, but it lacks random assignment of participants to conditions. The problem with this approach, of course, is that there might be differences between the two groups of students other than the style of teaching to which they were exposed.  Perhaps the students who signed up for the earlier section are more “gung ho.”  Or perhaps the students who signed up for the evening section are more likely to be working adults.  Or perhaps the students in the 1:00 p.m. section tend to be drowsy after lunch.  It is possible that differences in the dependent variable could have been caused by these differences rather than differences in teaching style.

Page 16: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

So what’s the problem with quasi-experiments?

Page 17: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

No random assignment! = a sort of experiment!

Other examples: boys vs girls, old vs. young

Page 18: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Naturalistic Observations

Naturalistic observation – viewing the subjects of an experiment in their natural habitat IMPORTANT: Subjects CANNOT

know they are being watched! Why is this important??

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CASE STUDY

Case study – a scientific biography of a group or person, very in depth look at a phenomena Most use long-term research to gather

tons of data in order to generate new hypotheses

Utilize lots of different tests to collect data

ex) facial agnosia, split brain patients

Page 20: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Surveys

Surveys – an interview/questionnaire that gathers data on the attitudes, beliefs, and experiences of large numbers of people

Page 21: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Longitudinal Studies

Longitudinal studies – covers a long period of time, same subjects followed for long time and questioned at different intervals in time (ex. Age 20, 25, 30 35)

Psychologists study subjects over regular intervals for a period of years Allows for examination of

consistencies and inconsistencies as development occurs

Page 22: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Cross-sectional

Cross-sectional studies – individuals are organized/studied on the basis of age

Question different groups of people that represent different stages of development

Page 23: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Avoiding Errors

How can researchers avoid errors while doing research? self-fulfilling prophecy - Researchers finding

what they want to find, while overlooking contrary evidence

Example experiment – testing a new medicine Single Blind – subjects do not know if they

have a are in control group (placebo) or in the experimental group ( get real IV)

Double Blind – subjects AND experimenter have no knowledge of who in is experimental or control group = best option if possible to design

Page 24: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Smile Break

Page 25: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Statistics

A branch of mathematics that enables researchers to organize and evaluate the data they collect

Page 26: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Statistics

Descriptive statistics – listing and summarizing data in a practical and efficient way Examples – graphs, averages

Page 27: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Statistics

Frequency distribution – table that arranges data in a way that allows us to see how often a particular score occurs

Histogram – similar to bar graphs – always vertical & the bars always touch

Frequency polygon – no bars just lines to visually display data

Page 28: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Frequency Distribution

Page 29: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Histogram

Page 30: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Frequency Polygon

Page 31: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Central Tendency

Central tendency – a number that describes something about the “average” score Used to summarize information into statistics

Measures of CT: mean, median mode

Page 32: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Central Tendency

Mean – an “average” score Most commonly used measure of CT

To find the mean, you add all scores and divide by the number of scores

Page 33: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Central Tendency

Median – the middle score The midpoint of a set of scores, so it divides the frequency distribution into two halves

Mode – the most frequent score

Page 34: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Central Tendency

0, 3, 4, 4, 5, 5, 6, 7, 8, 8, 8, 9, 9, 10, 10

Mean – 6.4 Median – 7 Mode - 8

Page 35: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Measures of Variance

Distributions show us not only the “average” score, but also how “spread out” these scores are.

Variance – provides an index of how spread out the scores of a distribution are

Page 36: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Measures of Variance

Range – subtract the lowest score from the highest score

Standard deviation – a measure of distance, describing an “average” distance of every score to the mean The larger the standard deviation,

the more spread out the scores are

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Page 38: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Standard Deviation

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Inferential Statistics Used to determine whether or not the

data that researchers collect supports their hypotheses, or whether their results are merely due to chance outcomes, draw conclusions & interpret data probability & chance

If probability that results are due to chance is less than 5% ( .05), researchers can be confident in their findings (less than 1 in 20 chance)

Page 42: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Ethical Guidelines

Read page 59

Page 43: CHAPTER 6 Psychological Research and Statistics. Objectives  Describe the process of psychological research  Name the different types of psychological

Define for Homework, Chapter 6Population Placebo effectSample Demand characteristicsExperimental group CounterbalancingControl group ReliabilityBetween subject design Ex post factoWithin subject design BimodalConfounding variables MultimodalOperational definition Skewed distribution Random Assignments Meta-analysisExperimenter Bias