Central Tendency
A. Measures of Central Tendency
A measure of central tendency is a statistic that indicates the middle, center or average of a distribution;
provides a single score to represent the entire group of scores.
1. Mean:
Arithmetic average; takes into account the value of each and every score in the distribution;
considered the balance point, or fulcrum, of the distribution
M =
N
X
∑
Examples
1) Data set: 2, 3, 4, 5, 5, 5, 6, 6, 6, 7, 8, 9
2) Data set: 2, 3, 4, 5, 5, 5, 6, 6, 6, 7, 20, 21
2. Median:
Score that divides the distribution in half such that half of the scores are greater and half of the
scores are less than the median (Mdn)
Median location =
2
1
+
N
=
th
score
Put scores in order and count from one end to median location. The score at that location is the median.
Examples: 1)
Data set: 2, 3, 4, 5, 5, 5, 6, 6, 6, 7, 8, 9
2)
Data set: 2, 3, 4, 5, 5, 5, 6, 6, 6, 7, 20, 21
3) Frequency distribution:
X
f
7
4
6
9
5
24
4
19
3
10
2
7
1
6
3. Mode:
The most frequently occurring score in the distribution
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview.
Sign up
to
access the rest of the document.
 Fall '08
 Burns
 Mean

Click to edit the document details