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Targeted Connections: Targeted Connections: Experimental Design Experimental Design and Data Analysisand Data Analysis
Margaret Buerman Margaret Buerman [email protected]@nwmissouri.edu
Patricia Lucido Patricia Lucido [email protected]@nwmissouri.edu
Cheryl Malm Cheryl Malm [email protected]@nwmissouri.edu
Northwest Missouri State UniversityNorthwest Missouri State University
Scientific MethodsScientific Methods
ObservationObservation – – No cause and effect methodologyNo cause and effect methodology Bird count, plant survey, genetic trait countBird count, plant survey, genetic trait count
CorrelationCorrelation Plant survey with observations of Plant survey with observations of
environmentenvironment Experimental DesignExperimental Design
Define an independent variable, dependent Define an independent variable, dependent variable and constantsvariable and constants
Planning ExperimentsPlanning Experiments
8 Steps to the Plan8 Steps to the Plan
Starting with Cothron, Giese, Rezba’s Starting with Cothron, Giese, Rezba’s Students and ResearchStudents and Research
What materials are available What materials are available for experimenting with ____?for experimenting with ____?
What materials / conditions are available What materials / conditions are available for conducting experiments on yeast?for conducting experiments on yeast? Growth nutrientsGrowth nutrients TemperatureTemperature Light conditionsLight conditions pH of the mediumpH of the medium
Q 1
How can the available How can the available materials be materials be changedchanged??
How can the materials / conditions be How can the materials / conditions be changed to affect yeast?changed to affect yeast? Growth medium: % concentration of Growth medium: % concentration of
ingredients, liquid or solidingredients, liquid or solid Temperature: constant, variable temp, Temperature: constant, variable temp, Light conditions: natural, artificial, time of Light conditions: natural, artificial, time of
exposure (UV sensitive vs normal)exposure (UV sensitive vs normal) pH: values from 4 to 8pH: values from 4 to 8
Q 2
How do ____ act?How do ____ act?
How do yeasts act?How do yeasts act? Grow Grow
Form colonies on solid mediumForm colonies on solid mediumChange in turbidity in liquid mediumChange in turbidity in liquid medium
Form pigmentsForm pigments
Q 3
How can response to the How can response to the change be measured?change be measured?
For yeastFor yeast Count number of coloniesCount number of colonies Change in turbidityChange in turbidity Observe color of coloniesObserve color of colonies Record shape of coloniesRecord shape of colonies Observe changes in cell shape under Observe changes in cell shape under
microscopemicroscope
Q 4
The Experimental Design The Experimental Design PlanPlan
The Effect of Sunlight on Yeast GrowthThe Effect of Sunlight on Yeast Growth Possible HypothesesPossible Hypotheses
H1: H1: The longer the yeast are exposed to The longer the yeast are exposed to sunlight, the fewer the number of colonies.sunlight, the fewer the number of colonies.
Ho:Ho: The mean number of yeast exposed to UV The mean number of yeast exposed to UV light will equal the mean number of yeast not light will equal the mean number of yeast not exposed to UV light.exposed to UV light.
Ho:Ho: The mean mass of yeast exposed to UV The mean mass of yeast exposed to UV light will equal the mean mass of yeast not light will equal the mean mass of yeast not exposed to UV light.exposed to UV light.
What is the What is the Experimental Plan?Experimental Plan? TitleTitle HypothesisHypothesis Independent VariableIndependent Variable ControlControl Levels of the Independent VariableLevels of the Independent Variable Number of TrialsNumber of Trials Dependent VariableDependent Variable ConstantsConstants
The Effect of Sunlight on Yeast GrowthThe Effect of Sunlight on Yeast Growth
The longer the yeast exposure to sunlight, the The longer the yeast exposure to sunlight, the fewer the number of colonies formed.fewer the number of colonies formed.
Independent Variable: The amount of sunlight
0 minutes (control)
5 minutes
10 minutes
15 minutes
3 trials
3 trials
3 trials
3 trials
Dependent Variable: the number of coloniesConstants: same pH, growth medium, temperature
What equipment and What equipment and measurement tools are measurement tools are
necessary?necessary?
Means of detection or measurement:Means of detection or measurement:
EyeEye MicroscopeMicroscope Drying ovenDrying oven BalanceBalance
Q 5
What kind of data are What kind of data are collected?collected?
Types of Data in terms of:Types of Data in terms of: Discrete – only whole integersDiscrete – only whole integers
number of yeast coloniesnumber of yeast colonies
Continuous – divisible into partial unitsContinuous – divisible into partial units dry mass of yeast dry mass of yeast
Types of Data in terms of:Types of Data in terms of: Quantitative – plate counts, mass Quantitative – plate counts, mass
measurementmeasurement Qualitative – pigment color (nominal)Qualitative – pigment color (nominal)
Q 7
Quantitative DataQuantitative Data
Scale of equal intervals that are continuous Scale of equal intervals that are continuous (or discrete)(or discrete)
Interval Level of MeasurementInterval Level of Measurement An arbitrary zero (C or F temperature)An arbitrary zero (C or F temperature) Cut grass to same height, observe growthCut grass to same height, observe growth
Ratio Level of MeasurementRatio Level of Measurement An absolute zero (height, Kelvin temperature)An absolute zero (height, Kelvin temperature) Height of the plantsHeight of the plants
Discrete QuantitativeDiscrete Quantitative Number of Yeast Colonies vs Time of
Exposure to Sunlight
020406080
100120
5 10 15 20
Time (minutes)
Nu
mb
er
colonies
time m 5 10 15 20colonies 100 75 45 30
Continuous Quantitative DataContinuous Quantitative DataDry Mass of Yeast vs Time of Exposure
to Sunlight
00.20.40.60.8
11.2
0 5 10 15
Time (minutes)
Mas
s in
mil
ligr
ams
Mass mg
time min 0 5 10 15Mass mg 0.98 0.72 0.47 0.28
Discrete Data - Whole Discrete Data - Whole IntegersIntegers
Number of snails in the terrarium vs TimeNumber of snails in the terrarium vs Time
Snails in Terrarium
02468
10121416
1 2 3 4
Time (weeks)
Num
ber
snails
Continuous DataContinuous Data
Scales that are divisible into parts.Scales that are divisible into parts.
Height of FAST Plants vs Time
02468
101214
0 1 2 3 4
Time (weeks)
Hei
ght
in c
m
Height
Qualitative DataQualitative Data Nonstandard scales of discrete or categorical dataNonstandard scales of discrete or categorical data
The plants appear stressed or wiltedThe plants appear stressed or wilted Leaf conditionLeaf condition
Nominal Level of MeasurementNominal Level of Measurement No ranking (gender, eye color, plant variety)No ranking (gender, eye color, plant variety)
Ordinal Level of MeasurementOrdinal Level of Measurement Ranked data (order in a race, line up from tallest Ranked data (order in a race, line up from tallest
to shortest)to shortest) Germination order 1Germination order 1stst, 2, 2ndnd, 3rd …., 3rd ….
What kind of data display What kind of data display is appropriate?is appropriate?
Scatter plotsScatter plots Box and WhiskersBox and Whiskers HistogramsHistograms Bar Graphs Bar Graphs Pie ChartsPie Charts Frequency DistributionFrequency Distribution Line GraphsLine Graphs
Q 8
What Statistical Descriptions What Statistical Descriptions Are Appropriate?Are Appropriate?
Descriptive statisticsDescriptive statistics Central TendencyCentral Tendency
VariationVariation
Inferential statisticsInferential statistics t Testt Test Chi-Square Chi-Square
Q 9
Descriptive Statistics for Descriptive Statistics for DataData
The data’s The data’s central tendenciescentral tendencies.. MeanMean Median Median (not for nominal data)(not for nominal data)
ModeMode
Descriptive Statistics for Descriptive Statistics for Data Data
Measure of Variation or SpreadMeasure of Variation or Spread Range – quantitative dataRange – quantitative data Interquartile RangeInterquartile Range Boxplot (Box and Whisker)Boxplot (Box and Whisker) Frequency Distribution – qualitative dataFrequency Distribution – qualitative data Stem-and-Leaf DiagramStem-and-Leaf Diagram Standard DeviationStandard Deviation
Data DescriptionData Description
Compare the MediansCompare the Medians Compare Boxes and Interquartile range Compare Boxes and Interquartile range Describe Symmetry of the distributionDescribe Symmetry of the distribution Describe Range of valuesDescribe Range of values Mention OutliersMention Outliers Hypothesis supportHypothesis support
Inferential StatisticsInferential Statistics
Are the findings for a small sample likely Are the findings for a small sample likely to represent a larger group?to represent a larger group?
t Testt Test
Chi squareChi square
The t TestThe t Test (uncorrelated with equal sample size)(uncorrelated with equal sample size)
Use the t test to determine if the quantitative Use the t test to determine if the quantitative difference between the means is statistically difference between the means is statistically significant.significant.
H1: H1: The longer the yeast are exposed to The longer the yeast are exposed to sunlight, the fewer the number of colonies.sunlight, the fewer the number of colonies.
Ho:Ho: The mean number of yeast exposed to The mean number of yeast exposed to UV light will equal the mean number of yeast UV light will equal the mean number of yeast not exposed to UV light.not exposed to UV light.
Chi-square testChi-square test
Use the Chi-square (Use the Chi-square (X X 22) to determine if ) to determine if the differences between frequency the differences between frequency distributions in qualitative data are distributions in qualitative data are statistically significant.statistically significant.
Ho: The frequency distribution of plant Ho: The frequency distribution of plant height is not significantly different from height is not significantly different from the frequency distribution predicted by the frequency distribution predicted by chancechance
Chi-square testChi-square test
onDistributiFrequencyExpectedE
onDistributiFrequencyObserved
valuestheofSum
squareChi
E
E
2
22
ResourcesResources
Students and Research Students and Research Cothron, Giese, Rezba Cothron, Giese, Rezba ISBN 0-7872-6477-6ISBN 0-7872-6477-6
The Cartoon Guide to StatisticsThe Cartoon Guide to Statistics by Larry Gonick by Larry Gonick
Biological Experiments and Activities Integrating Biological Experiments and Activities Integrating MathematicsMathematics by Stephen Rodecker and Jim by Stephen Rodecker and Jim PatzoldPatzold
http://mathforum.orghttp://mathforum.org
