A Stata Companion to Political Analysis

Philip H. Pollock

SAGE Publications, May 15, 2006 - Political Science - 217 pages

Tables and Figures ix Preface xiii Getting Started 1 Copying the Data Files to Floppy Disk or Other Portable Media 2 How to Handle the Datasets 2 Contents of the Datasets 4 Notes 4 Introduction to Stata 5 Commands Covered describe, codebook, set more off, search, help Changing General Preferences 5 Obtaining Information about a Dataset 6 Obtaining Information about Variables 9 Creating and Viewing a Log File 10 A Closer Look Obtaining Specific Variable Information with Define Notes 11 Printing Results 13 Getting Help 13 Exercises 17 Notes 17 Descriptive Statistics 19 Commands Covered tab1, summarize, sktest, histogram, Submit button Interpreting Measures of Central Tendency and Variation 19 Describing Nominal Variables 20 Describing Ordinal Variables 21 Describing Interval-level Variables 23 Obtaining Bar Charts and Histograms 27 Creating Bar Charts 27 Creating Histograms 32 A Closer Look The Submit Button and the OK Button: What's the Difference? 33 Exercises 35 Notes 40 Transforming Variables 43 Commands Covered recode, generate; generate, recode; xtile, nquantiles; generate; tabulate, generate; label variable; label define; label values; drop; aorder Transforming Categorical Variables 44 Transforming Interval-level Variables 46 A Closer Look The xtile Command 48 The label define and label values Commands 51 Creating an Additive Index 51 Creating Indicator Variables 53 Exercises 55 Notes 58 Making Comparisons 59 Commands Covered tabulate, column; tabulate, summarize; graph bar; format; replace Cross-tabulation Analysis 59 Mean Comparison Analysis 60 A Closer Look The format Command 62 Visualizing Relationships with Bar Charts 62 Graphing an Interval-level Dependent Variable 63 Graphing a Categorical Dependent Variable 67 A Closer Look The replace Command 70 Exercises 73 Notes 83 Making Controlled Comparisons 85 Commands Covered (prefix) bysort:, tabulate, col; tabulate, summarize; graph bar; if Cross-tabulation Analysis with a Control Variable 86 A Closer Look The if Qualifier 88 Bar Charts for Controlled Comparisons with a Categorical Dependent Variable 89 Mean Comparison Analysis with a Control Variable 91 Bar Charts for Controlled Comparisons with an Interval-level Dependent Variable 96 Exercises 98 Notes 105 Making Inferences about Sample Means 107 Commands Covered ttest; ttest, by; robvar, by Describing a Sample Mean 108 Testing the Difference between Two Sample Means 111 Exercises 116 Notes 118 Chi-square and Measures of Association 121 Commands Covered (tabulate option) chi2; (tabulate option) taub; (tabulate option) V; somersd; lambda; which; ssc install Installing lambda and somersd 122 Analyzing Ordinal-level Relationships 122 Analyzing Nominal-level Relationships 127 A Problem with Lambda 129 Exercises 130 Notes 136 Correlation and Linear Regression 137 Commands Covered correlate; regress; graph twoway (scatter); graph twoway (scatter)(lfit) The correlate Command and the regress Command 137 Creating a Scatterplot 139 A Closer Look R-squared and Adjusted R-squared: What's the Difference? 140 Exploring Multivariate Relationships with Regression 147 Exercises 150 Notes 156 Dummy Variables and Interaction Effects 159 Commands Covered xi: regress; char [omit]; test Regression with Dummy Variables A Closer Look The test Command 162 Interaction Effects in Multiple Regression 164 Graphing Linear Prediction Lines for Interaction Relationships 167 Exercises 173 Notes 178 Logistic Regression 181 Commands Covered logit; logistic; estimates store; Irtest, force; predict; adjust, by pr gen; quietly:; tabstat, by The logit Command and the logistic Command 182 Logistic Regression with Multiple Independent Variables 185 A Closer Look The estimates Command and the Irtest Command 187 Working with Predicted Probabilities: Models with One Independent Variable 188 Working with Predicted Probabilities: Models with Multiple Independent Variables 191 Exercises 196 Notes 201 Doing Your Own Political Analysis 203 Commands Covered insheet Five Doable Ideas 203 Political Knowledge 204 Economic Performance and Election Outcomes 204 State Courts and Criminal Procedure 204 Electoral Turnout in Comparative Perspective 205 Congress 205 Doing Research on the U.S. Senate 205 Finding Raw Data 206 How to Code Raw Data 206 A Closer Look The Stata Data Editor 208 Two Possible Coding Shortcuts 210 Importing Text Data 212 Writing It Up 215 The Research Question 215 Previous Research 216 Data, Hypotheses, and Analysis 216 Conclusions and Implications 216 Notes 217.

Contents

• Getting Started: 1
• Obtaining Information about Variables: 9
• 115: 16

About the author

Philip H. Pollock III is a professor of political science at the University of Central Florida. He has taught courses in research methods at the undergraduate and graduate levels for more than thirty years. His main research interests are American public opinion, voting behavior, techniques of quantitative analysis, and the scholarship of teaching and learning. His recent research has been on the effectiveness of Internet-based instruction. Pollock's research has appeared in the American Journal of Political Science, Social Science Quarterly, and the British Journal of Political Science. Recent scholarly publications include articles in Political Research Quarterly, the Journal of Political Science Education, and PS: Political Science and Politics.

Bibliographic information

• Title: A Stata Companion to Political Analysis
• Author: Philip H. Pollock
• Edition: illustrated, revised
• Publisher: SAGE Publications, 2006
• ISBN: 0872893057, 9780872893054
• Length: 217 pages
• Subjects: Political Science / History & Theory; Political Science / International Relations / General; Political Science / Public Policy / Economic Policy; Political Science / Reference; Social Science / Research