Question

A) A child psychologist conducts a study to test whether infants born prematurely begin to walk earlier than do infants in general. If the research hypothesis is actually true – infants born prematurely do begin to walk earlier than infants in general – and the psychologist has a 25% chance of making a Type II error, what is the power of the study? (give your answer as a proportion - between 0 and 1)

B) If there really is NOT a relationship in the population, what is the probability of NOT rejecting the null hypothesis if a .01 significance level is used? (give your answer as a probability - between 0 and 1 - not as a percentage)

C) A psychologist investigating hearing thresholds knows that an average participant gets a score of 42 with a standard deviation of 15 on a standard hearing test. The psychologist adds a distraction task to the standard test for a sample of 10 participants and evaluates the effect of the distraction at the .01 level. The distraction results in a 12-point reduction in scores.

Calculate an estimated Cohen’s d for this result

D) A psychologist investigating hearing thresholds knows that an average participant gets a score of 42 with a standard deviation of 15 on a standard hearing test. The psychologist adds a distraction task to the standard test for a sample of 10 participants and evaluates the effect of the distraction at the .01 level. The distraction results in a 12-point reduction in scores.

Explain, in words, what this means (hint: what units is Cohen’s d in?)

E) A psychologist investigating hearing thresholds knows that an average participant gets a score of 42 with a standard deviation of 15 on a standard hearing test. The psychologist adds a distraction task to the standard test for a sample of 10 participants and evaluates the effect of the distraction at the .01 level. The distraction results in a 12-point reduction in scores.

How large is this effect, based on Cohen’s guidelines?

Answer: (1) small, (2) medium, (3) not enough information to answer, (4) large

F) If the human-factors department of a large corporation is planning to test a group of employees to see if ergonomically designed workstations really improve the speed and accuracy with which employees are able to perform their work, what are three things the department can do to make the power of the planned study high? List only things that are appropriate to the goals of the research. Be specific. (That is, name or describe the statistical principles and then describe how each works to increase power.)

Answer 1

(A)----------- Type- I error ----- It means hypothesis is rejected, when in reality hypothesis is true.

Type- II error ---- It means retain of hypothesis, when in reality hypothesis is false.

Level of significance is that level in which the researcher do eccept or reject the Null Hypothesis. Both level of significance means, 0.01 or 1% and 0.05 or 5% levels. In one of these level hypothess got rejected when in reality it is true. when we try to control type one error at 0.01 level, chances increase in commeting beta error.

hence if there is 0.25 chances of commeting type 2 error there is greater chnace of acceptance of hypothesis because the controls the 0.05 level of alpha error.

(b)-------- The probability of NOT rejecting the null hypothesis if a .01 significance level is explained as under It important that the obtained statistical value is equal(=) or greater(>) that the given 0.01 & 0.05 stastical value to reject the null hypothesis, hence there is 0% probability of, NOT rejecting the null hypothesis at a .01 significance level

for C , D ,E question please revert me , I will get back .