Answer all the questions basis on Statistical Decisions

Statistical decision 1:

     A researcher compared the number of cavities of children who had used either Toothpaste brand X or Toothpaste brand Y for a year. At the end of the year, the researcher found that the children who had used brand X had significantly fewer cavities than the children who had used brand Y. The 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?

Statistical decision 2:

     The effect of a monetary incentive on performance on a cognitive task was investigated. The researcher predicted that greater monetary incentives would result in higher performance. Participants were told that they would receive either 5 cents, 25 cents, or 50 cents for each word puzzle that they correctly solved. A statistical test showed that there was a significant effect of incentive on performance at the .01 level. The greater the incentive, the more puzzles were solved.

 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?

Statistical decision 3:

     A researcher investigated whether job applicants with popular names are viewed more favorably than equally qualified applicants with less popular names. Participants in one group read a resume of a job applicant with a popular name; participants in the other group read the same resume but the applicant had an unpopular name. There were five participants in each group. The results showed that the difference in evaluation of the applicants was not significant (p < .22).

 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?

Statistical Decision 4:

   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?