STEP-BY-STEP TECHNOLOGY GUIDE: Sign Test

14-15

TI-83/84

The TI-83/84 calculator does not have a built-in sign test function. However, you can use the binomcdf( function to calculate the p-value for a sign test.

  • Step 1 Press 2nd, VARS, scroll down and select binomcdf(, and press ENTER.
  • Step 2 The entry should be binomcdf (n, p, x), with
    • n = the sum of the number of pluses and minuses
    • p = 0.5
    • x = the value of Sdata (from Table 3)
  • Step 3 Press ENTER. The result is the p-value for a one-tailed test. Double this value for a two-tailed test. Reject H0 if the p-value is less than α.

EXCEL

Excel does not have a built-in sign test function. However, you can use the BINOMDIST function to calculate the p-value for a sign test.

  • Step 1 On the main menu bar, click fx Where it says Search for a function, type BINOMDIST and click Go. Where it says Select a function, select BINOMDIST and click OK.
  • Step 2 In the dialog box, enter the following values: For Number_s, enter the value of Sdata (from Table 3) For Trials, enter n = the sum of the number of pluses and minuses. For Probability_s, enter 0.5. For Cumulative, type True.
  • Step 3 Click OK. The result is the p-value for a one-tailed test. Double this value for a two-tailed test. Reject H0 if the p-value is less than α.

MINITAB

  • Step 1 If you are performing the sign test for a single population median, enter the original data into column C1. If you are performing the sign test for the population median of the differences, enter the difference data into column C1.
  • Step 2 Select Stat > Nonparametrics > 1-Sample Sign….
  • Step 3 For the Variables cell, select C1. Select Test Median, and enter the hypothesized value of the median, M0. Select the direction of the alternative hypothesis, and click OK.

SPSS

  • Step 1 Enter the data into the first column. Under Variable View, rename the first variable, and name the second (currently empty) variable Sign.
  • Step 2 Click Transform > Compute Variable….
  • Step 3 Under Target Variable type Sign, and under Numeric Expression enter the first variable, a less-than sign (<), and then M0. Click OK twice.
  • Step 4 Select Data > Select Cases. Click If condition is satisfied, click If…, and enter the first variable, the “not equals” button, and then M0. Click Continue.
  • Step 5 Under Output, select Filter out unselected cases. This will ignore values that do not have a sign associated with them. Click OK.
  • Step 6 Click Analyze > Nonparametric Tests > Legacy Dialogs > Binomial….
  • Step 7 Move Sign to Test Variable List, and under Test Proportion put 0.50, and click OK.

JMP

JMP does the sign test for matched pairs only.

  • Step 1 Click File > New > Data Table. Enter the two samples in the first two columns.
  • Step 2 Click Analyze > Matched Pairs. Move both columns to Y, Paired Response. Click OK.
  • Step 3 Click the arrow beside Matched Pairs, and select Sign Test. The output using Example 6 is shown in Figure 5.