What does Step 2 of the sign test involve?

What does Step 2 of the sign test involve?

• A. Determine the sum of absolute differences.
• B. Add up the number of + and - signs; ignore ties.
• C. Compute a t-statistic from the signed differences.
• D. Rank the differences.

Answer: (B)

The sign test looks at simply the direction of each paired difference, not how large those differences are. Step 2 is to count how many of the differences are positive and how many are negative, ignoring any cases where the difference is zero (ties). This tally of plus and minus signs (out of the non-tied pairs) becomes the data for the binomial test under the null hypothesis that positive and negative differences are equally likely. The other options describe actions from other tests or from different parts of the sign test: summing absolute differences is used in methods that consider magnitudes, computing a t-statistic is for parametric tests, and ranking the differences is part of the Wilcoxon signed-rank test.

The sign test looks at simply the direction of each paired difference, not how large those differences are. Step 2 is to count how many of the differences are positive and how many are negative, ignoring any cases where the difference is zero (ties). This tally of plus and minus signs (out of the non-tied pairs) becomes the data for the binomial test under the null hypothesis that positive and negative differences are equally likely. The other options describe actions from other tests or from different parts of the sign test: summing absolute differences is used in methods that consider magnitudes, computing a t-statistic is for parametric tests, and ranking the differences is part of the Wilcoxon signed-rank test.