Example: New scores on the Roberts Test of Agricultural Knowledge: 90 70 95 65 80 85 70 75 75 60

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