Supplemental speaking notes for October 29, 2009

PADM 5502

Dr. Neubauer

The course calendar says we should be studying UNIVARIATE STATISTICS this evening. These are usually reported first in the FINDINGS section of your paper. In other words, HOW MAY females and males were in the sample? What was the average age of the respondents? What was the range of incomes, and so forth.

There are three usual measures of CENTRAL TENDENCY.

• mean
• median
• mode

There are three usual measures of DISPERSION.

• range
• interquartile range
• standard deviation

Interval level date is the most PRECISE and you can do "better" statistics on it.

If you have interval level data you can "down grade it" to ordinal if needed.

If you have ordinal data you cannot "upgrade" it to interval. If you collect family income in ranges you cannot than figure out the exact values. If you have exact values you can create ranges.

THREE MAJOR MEASURES OF CENTRAL TENDENCY -- mean, median, mode

	Mean	Median	Mode
Nominal	no	no	yes
Ordinal	no	yes	yes
Interval	yes	yes	yes

Regarding the measures of DISPERSION, the same applies. Interval data is "better" than the others.