Next: Measures of Spread
Up: Numerical Descriptive Statistics
Previous: Numerical Descriptive Statistics
- The average of all the values in the sample
(population). We usually denote the mean of a sample by putting a bar
on top of whichever letter we use to represent the sample: e.g.,
.
- The center point of the sample (population). More
specifically, a number such that at least half of the values in a
sample (population) are less than it and half of the values are
greater than it. We often denote the median by putting a tilde on top
of whichever letter we use to represent the sample: e.g.,
.
- Mechanics:
- Order the data from smallest to largest.
- If n is odd,
is the middle value. - If n is even,
is the average of the two middle
values.
- The value which occurs most frequently in the sample
(population). If the sample (population) has only one mode, it is
called unimodal. If it has two modes, it is called
bimodal; if it has more than two modes: multimodal. The mode
is a good measure of central tendency only for a symmetric, unimodal
sample (population).
Jan Lethen
Wed Nov 13 16:20:46 CST 1996