1. Descriptive Statistics
PSY 330 Research Methods

2. Measurements Choices Determine Analysis Options
Choice of measure occurs in research design
Measures yield data at a particular scale (level) of measurement (Nominal, Ordinal, Interval, Ratio)
Interval or Ratio data can be recoded to create groups (e.g., age groups, income ranges)
Grouped data cannot be expanded to create Interval or Ratio data
Scale (Level) of Measurement determines which techniques are appropriate.
3. Matching Average to Data
4. Matching Variability Measure to Data
Range and Interquartile Range (IQR) use only a few scores.
Standard deviation and variance use the value of each score in the data set
Range and IQR are related to Median
Standard Deviation and Variance are related to the Mean.
5. Purpose of a Graph
A visual presentation of data
Relationships & comparisons are visual
Less daunting to some than tables of numbers
Allows some artistry and creativity
Accuracy is important
Characteristics of data
Measurement choicesin design determine analysis choices later
Scale (level) of measurement determines which graphs can be used
Nature of the particular data set is also important
6. Graphs for Complex Data
The Future of Food. (2008) WiredMagazine 16:11
From ChoiceRanker website via JunkCharts blog at http://junkcharts.typepad.com/junk_charts/2008/07/its-raining-colors-here-too.html
7. Basic requirements for graphs

Axes drawn and labeled

8. Category values labeled 9. Title for graph 10. Data bars proportional tonumber of cases in data 11. Balanced 12. Maintains scale 13. No chart junk 14. Not complicated 15. Does not convey too much