User Guide

489
Nonparametric
Te s t s
Runs Test
The Runs Tes
t procedure tests whether the order of occurrence of two values of a
variable is random. A run is a sequence of like observations. A sample with too many
or too few runs suggests that the sample is not random.
Examples. S
uppose that 20 people are polled to find out if they would purchase a
product. The assumed randomness of the sample would be seriously questioned if
all20peoplewereofthesamegender.Therunstestcanbeusedtodetermineifthe
sample was
drawn at random.
Statistics. Mean, standard deviation, minimum, maximum, number of nonmissing
cases, and quartiles.
Data. The v
ariables must be numeric. To convert string variables to numeric variables,
usetheAutomaticRecodeprocedure, available on the Transform menu.
Assumptions. Nonparametric tests do not require assumptions about the shape of the
underlyi
ng distribution. Use samples from continuous probability distributions.
Figure 34-7
Runs Test output
1.00
7
13
20
15
2.234
.025
Test Value
1
Cases < Test Value
Cases >= Test Value
Total Cases
Number of Runs
Z
Asymptotic
Significance (2-tailed)
Gender
Runs Test
Median
1.