Elementary Analysis Richard LeGates URBS 492

Univariate Analysis Distributions –SPSS Command Statistics | Summarize | Frequencies Presents label, total cases, number of valid and and missing values For valid cases: frequency, percent, valid percent, and cumulative percent Frequency | Percent |Valid percent | Cumulative percent –SPSS Command Graph | Bar Visual representation of frequency distribution Enter Title before running procedure Select Bars Represent: percents To edit Bar chart: In data editor Useful change: change color of bars to black | swap axes | label bars with % To copy from SPSS Data Editor to Word: Right Click | Copy | in Word: Paste

Central Tendency Data reduction to make Data understandable (Good in data description or exploration) SPSS Procedure: Statistics | Summarize | Descriptives –Mode: Good for nominal level data. Most common occurrence. –Mean: Good for ratio level data. Sum of cases / number. Be careful about “outliers”. A few high or low values make it misleading. –Median: Good for ratio level data. “Middle” case. Avoids misleading effect of outliers. –Standard deviation of mean. 95% of cases fall within +/1 SD of mean Dispersion –Min and Max Range: Good for ratio level data. Shows extreme values.

Subgroup Comparisons Often appropriate to describe subsets of sample. E.g. Men vs. Women; Undergrad vs. Grad Collapsing Response Categories –Where there are too many categories for reader to grasp easily; –Where there are few values in one or more categories Handling “Don’t Know” (DK) repsonses –Depends on research situation. –Report how many DK responses received. Analyze only valid cases. This will give you an analysis of those who did respond; –Analyze including DKs. This will give you an analysis of all respondants

Bivariate Analysis “Bi” means 2. Analysis of two variables Useful for –Cleaning data. Look for implausible values –Description –Explanation. Dependent variable explained in terms of independent variable Basic bivariate analyses –Crosstabs Statistics | summarize | Crosstabs –Scattergrams: Graphs | Scatter –Correlation: Statistics | Correlate | Bivariate

Percentaging Tables We are usually interested in percents; not absolute values Enter dependent variable first (as row variable) Enter independent variable second (as column variable) Select column percent from cells In reading the crosstab percentage down. Each column will = 100% Variations –Enter column, row, and/or total percents –Uncheck the cells | counts | observed box to get percents only.

Babbie’s Bivariate Table Format Rules Heading succinctly describing table Understandable Variable labels (with explanation in text or appendix as needed) Attributes of each cell clear Indicate base on which percentages computed Indicate missing data and explain

Moving SPSS Output into Word Processors Open Data Editor Open Word Processor Switch back to Data Editor (Window) Select and Copy Table or image –Left click on image once –From menu select: Edit | Copy Switch to Word Processor (Window) –From menu select: Edit | Paste Special | Picture