Part I of the Study Guide for Explaining Psychological Statistics, Third Edition
by Barry H. Cohen
Chapter 1
Introduction to Psychological Statistics
Measurement Scales
Nominal: Observations are assigned to categories that differ qualitatively, but have n
The Range. The range is the highest score minus the lowest. The number of books read ranged from 1 to
9, so range = 9 - 1 = 8. If the scale is considered continuous (e.g., 9 books is really anywhere between 8 1/2
and 9 1/2 books), then range = upper real
Chapter 3
Measures of Central Tendency and Variability
Advantages and Disadvantages of the Major Measures of Central Tendency
Advantages of the Mode:
1. Easy to find.
2. Can be used with any scale of measurement.
3. The only measure that can be used with
Sig. value in the ANOVA box will always be the same as the Sig. for your IV in the
Coefficients box, when you are using only one IV (i.e., predictor).
Creating scatterplots. To check the linearity of the relation between two variables visually, and
to loo
Chapter 10 Section D
Linear Regression
To compute a linear regression analysis in SPSS:
1.Select Regression from the ANALYZE menu, and then choose Linear
2. In the dialog box that opens, move the variable that you want to predict to the area
labeled Depe
Chapter 9 Section D
Linear Correlation
To compute the Pearson r in SPSS:
1. Select Correlate from the ANALYZE menu,
2. Then choose Bivariate
3. In the dialog box that opens, move the variables you wish to see correlated to the area
labeled Variables: to
iii. For any value specified for q, the function will tell you how much of that
particular noncentral t distribution is to the left of q.
c. Example: If the sizes of your two groups were 15 and 20, df would equal 33, and you
would type (q, 33, xxx) right
Chapter 8 Section D
Statistical Power and Effect Size
For power analysis in the two-group case, you need to work with a noncentral t
distribution, which is centered on delta (the noncentrality parameter). Note that there is a
different noncentral t distri
Chapter 2
Frequency Tables, Graphs, and Distributions
Guidelines for Frequency Distributions
The procedure for constructing a grouped frequency distribution can be summarized in terms of the
following steps and guidelines.
Step 1. Choose the width (i) of
Adjacent values: The upper adjacent value is the highest score in the distribution that is not higher than the
upper inner fence, and the lower adjacent value is similarly defined in terms of the lower inner fence of a
boxplot. The upper whisker is drawn