The test normally used to find out the significance of mean difference among four independent variables is (A) Z - test (B) Chi - square test (C) Partial correlation (D) Analysis of variance Correct Ans: (D) Explanation: In mass communication research, when you want to find out whether there are significant mean differences across four or more independent groups, you use Analysis of Variance (ANOVA). This method helps determine whether the variations between group means are due to actual effects or just random chance. For example, suppose a media researcher wants to study the effect of four different types of news content—political, entertainment, sports, and educational—on viewer engagement. To test if the mean engagement scores differ significantly across these four categories, they would apply ANOVA. It helps answer a critical question: Do these content types truly affect engagement differently, or are the differences just random noise? Here’s how ANOVA works: it compares the variance between group means with the variance within the groups. If the between-group variance is significantly larger, the test shows a statistically meaningful difference. Researchers can then conclude that at least one group differs significantly from the others. Let’s look at the incorrect options:(A) Z-test is generally used for comparing two means when the population variance is known.(B) Chi-square test examines relationships between categorical variables, not mean differences.(C) Partial correlation analyzes the relationship between two variables while controlling for others—it doesn’t test group mean differences. Therefore, the correct statistical test to analyze mean differences among four independent variables is (D) Analysis of Variance. In conclusion, ANOVA gives researchers the ability to make strong, data-backed decisions about media effects across different conditions. It ensures that their conclusions are not based on guesswork but on statistically significant evidence, especially when dealing with multiple independent groups.