# Understanding statistics : an introduction for the social sciences / Daniel B. Wright. Wright, Daniel B.

Bibliographic record and links to related information available from the Library of Congress catalog ```	Acknowledgements	viii

1	Statistics in Social Science Research	1
Conducting Scientific Research	2
Levels of Measurement	3
Sampling	7
Measures of Central Tendency: the Three Ms	11
Constants, Variables and Equations	16
Experimental and Non-experimental Research	20
Summary	23
Assignment	26

2	Introduction to Hypothesis Testing	29
Measures of Dispersion	29
The Normal Distribution and z Scores	33
The Standard Error of the Mean	35
Testing Hypotheses: What to Do with p	38
Summary	41
Assignment	44

3	Comparing the Means of Paired Data	49
Student's Paired t Test	49
Example: Political Attitudes	50
Another Example: a Very Satisfying Day	53
Confidence Intervals of the Mean	55
Assumptions of the t Test	57
Computer Example	58
Alternatives When the Variable is Not Normally Distributed	59
Distribution-free Techniques	61
Transforming the Variable	63
Summary	64
Assignment	64

4	Comparing the Means of Two Groups	68
The Group t Test: Formal Definitions	68
Two Examples	69
Comparing Group Standard Deviations	70
An Equation Form of the Group t Test	73
Assumptions of the Group t Test	74
Power Analysis	77

Comparing the Paired and Group t Tests	82
Summary	83
Assignment	84

5	Introducing Regression and Correlation	88
Scatterplots	88
Regression	90
Partitioning Sums of Squares	94
Example: Pollution and House Prices	95
Interpreting Regressions: the Overall Fit	98
Significance Testing	101
Assumptions for Significance	104
Examining Residuals	106
Alternatives When Assumptions Are Not Satisfied	109
Summary	112
Assignment	112

6	Comparing  Many Means: the Analysis of Variance Approach	116
Between-subjects Comparisons	116
Graphing Means	116
The Oneway Between-subjects ANOVA	118
ANOVA as an Equation	119
Partitioning the Sums of Squares in an ANOVA	121
Another Example: Study Habits	125
Planned and Unplanned Comparisons	126
Assumptions and Alternatives for a Between-subjects ANOVA	131
Repeated Measures or the Within-subject ANOVA	133
Graphing Within-subject Means	135
Calculations for Within-subject ANOVA	137
Computer Output and Syntax	139
Assumptions for the Repeated Measures ANOVA	141
Summary	142
Assignment	142

7	Comparing Proportions	146
Single Variables	146
Confidence Intervals	146
Hypothesis Testing	147
Using a Computer	151
Two-variable Problems	153
Another Example: What Is Science?	156
Collapsing	159
x2  : the Equation Approach	162
Graphing Techniques (Optional)	166

Summary	169
Assignment	169

172
Multiple Regression	173
Collinearity and the Partial Correlation	173
Predicting Crime from Several Variables	174
Low Temperatures and the Dropout Rate	180
ANCOVA	184
Multivariable ANOVA	188
Factorial Between-subjects Designs	190
Within-subject ANOVA	192
Mixed Between-subjects and Within-subject Designs	193
Summary of ANOVA	195
Analysing Categorical Variables	196
Loglinear Modelling with Three Variables	196
Logistic Regression	199
Graphing Three Variables	201
Overall Summary	203
Assignment	203