which statistical test is the correct choice for a problem
Ask yourself a series of questions to figure out which statistical test is the correct choice for a problem. Provide a law enforcement example using each of the following tests.
What level of measurement is the data?
NOMINAL (CATEGORICAL) OR ORDINAL ? Chi-Square.
How many variables are there?
One variable ? One Way Chi-Square.
(a) Use the mathematical formula or
(b) Set the data up to use in SPSS with Nonparametric Tests ? Chi-Square.
Two variables (both are nominal or ordinal) ? Two Way Chi-Square.
(a) Use the formula to calculate the expected frequencies for each cell and then compute chi-square or
(b) Set the data up to use in SPSS with Descriptive Statistics ? Crosstabs ? Statistics ? Chi-Square
INTERVAL OR RATIO ? t-tests or ANOVA
How many samples or groups are there?
One group ? Single Sample t-test.
(a) There will always be a population mean in the question.
(b) The population mean is entered in the Test Value box in the SPSS One Sample T-Test
Two Groups ? Independent Samples t-test or Dependent Samples t-test
Are the samples independent or dependent?
Two independent samples ? Independent Samples t-test.
(a) Two completely different groups, each measured once
Two Dependent samples ? Dependent Samples t-test.
(a) A single group that was measured twice.
(b) Paired Samples T-Test in SPSS
Three or more groups ? Analysis of Variance (ANOVA)