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Example:
New scores on the Roberts Test of Agricultural Knowledge:
90 70
95 65
80 85
70 75
75 60
Example: 76.5 75 70, 75
10.5
mean - arithmetic average median - 50th percentile mode - most frequently
occuring score standard deviation - measure
of variability, based on normal curve
Example:
frequency - the number of occurrences of a score– 90 = 1
– 85 = 1
– 75 = 2
– 80 = 1
– 70 = 2
– 65 = 1
– 60 = 1
Example:
60 65 70 75 80 85 90 950
0.5
1
1.5
2
60 65 70 75 80 85 90 95
Score
Histogram
Frequency
Example:
0
0.5
1
1.5
2
60 65 70 75 80 85 90 95Score
Frequency
Frequency Polygon
Descriptive Statistics
Percentage -- the frequency of a score as a percentage of the sample (population)
Correlation -- number describing the linear relationship of two variables (one group of subjects); use a scatterplot to check for nonlinear relationships
Descriptive StatisticsScatterplot
VariableA
VariableB
Line of best fit
Outlier
Outlier
Inferential Statistics
Continuous Data: Difference between more than two
groups, one ind. variable: Analysis of Variance (ANOVA) Difference between groups, more
than one ind. variable: Factorial ANOVA
Inferential Statistics
Continuous Data: Difference between groups, one ind.
variable, more than one dep. variable: Multiple Analysis of Variance (MANOVA) Difference between groups, more than
one ind. variable, more than one dep. variable:
Factorial MANOVA
Inferential Statistics
Continuous Data: Difference between groups, one ind.
variable, one dep. variable with a pretest:
Analysis of Covariance (ANCOVA) >1 ind. variable = Factorial ANCOVA >1 dep. variable = MANCOVA
Application -- Example
Dep. Variable: Achievement (test scores)
Independent Variable: Teaching method (3 levels)
Prestest? No ANOVA
Application -- Example
Dep. Variable: Achievement (test scores)
Independent Variable: Teaching method (2 levels)
Prestest? Yes ANCOVA
Application -- Example
Dep. Variable: Achievement (test scores), Attitudes (Likert scale)
Independent Variable: Teaching method (3 levels)
Prestest? No MANOVA
Application -- Example
Dep. Variable: Achievement (test scores)
Independent Variable: Teaching method (3 levels)
Other independent variable: sex (2 levels)
Prestest? No Factorial ANOVA
