Non - parametric tests are the statistical tests that measure the variable at: (A) probability level (B) ratio level (C) interval level (D) nominal level Correct Ans: (D) Explanation:Non-parametric tests measure variables at the nominal level. Nominal level data represents categories that have no inherent order. These tests do not rely on assumptions about the population's distribution, making them ideal for categorical data. On the other hand, parametric tests typically require ratio, interval, or probability level data, which involve specific assumptions about the distribution and characteristics of the data. These tests are more versatile and can handle nominal or ordinal data, which do not fit the requirements for parametric tests. Thus, nominal level is the correct answer.