CS 103 Day 20, Wednesday May 9, 2001

If you haven't already, get the SPSS Exam problems page.
If you haven't already, get the one page handout, "Day (19), 20, 21, + Assignment 15

• Asst 13
• Crosstabs:  What percent of A's are B's?  All the B's you count must be A's also (B&A's).  Divide that number by the number of A's.

Reading SPSS tables.  Find where the 100% is for your A, work back from there..
• Standard deviations from the mean:  z-scores for the whole group are measured in standard deviations from the mean, so the mean should be 0 standard deviations from the mean, and the standard deviations should be 1 standard deviation from the mean. (Note on notation.  1.18E-16 = 1.18 times 10 to the minus 16 power, or 0.000 000 000 000 000 118. )  But the two separate groups, males and females, might have average salaries quite different, when the z-scores came from the pooled group.
• Bar graph vs. histogram.  Bar graph has just labels for the bars on the x-axis.  Histogram has intervals, empty space if there are no observations in an interval (cf. cars.)  They show you different things.
• Asst 14
• Printing scatterplots:  The colors print quite badly--change colors (use the crayon button) so they can be seen.

My pet peeve--graphs that were clearly designed in color, then printed (illegibly) in black and white.

• Using Help, tutorials
• Scatterplots, more. More help?
• Sort
• Importing from Text or Excel