Question

A social psychologist predicted that ratings of an individual’s social desirability would be influenced by their physical attractiveness. Participants received photos of attractive, average, or unattractive individuals. The researcher found that the more attractive the individual, the higher their rating of social desirability. This difference was significant at the .05 level. 1. What is the null hypothesis? 2. What is the research hypothesis? 3. What would be the Type I error? 4. What would be the Type II error? 5. What is the probability of a Type I error?

Answer 1

Answer

it is given in the question that researcher found that the  more attractive the individual, the higher their rating of social desirability.

This means we can assume that the alternative hypothesis to be "higher level of attraction leads to higher rating of social desirability"

For null hypothesis, we will assume that the level of attraction has no effect on the rating of social desirability.

(1) Null hypothesis:- level of attraction has no effect on the rating of social desirability.

(2) Alternate hypothesis:- level of attraction has positive effect on the rating of social desirability.

(3) Type I error is defined as the rejection of true null hypothesis. So, in this case, type I error will be that "level of attraction has positive effect on the rating of social desirability, when in actual level of attraction has no effect on the rating of social desirability."

(4) Type II error is defined as the failure to reject the false null hypothesis. So, in this case, type II error will be that "level of attraction has no effect on the rating of social desirability, when in actual level of attraction has positive effect on the rating of social desirability."

(5) we know that the probability of making type I error is equal to significance level(in % terms). It is given that the significance level in this case is 0.05, so probability of making type I error is 0.05*100= 5%

So, there is 5% probability of making type I error.