Aresearcher wanted to know whether losing one night sleep can affect problem solving. a sample of n = 25 college students was given a problem-solving task at noon on one day and again at noon on the following day. the students were not permitted any sleep between the two tests. for each student, the difference between the first and the second score was recorded: md = 4.7 and standard deviation of the difference score was s = 8.

do the data indicate a significant change in problem solving ability? use a two-tailed test with α = .05.

a)

the null hypothesis in words is :

problem solving ability improves after losing on night sleep

problem solving ability is reduced after losing one night of sleep

there is no significant difference in problem solving ability between the two conditions: before and after losing one night of sleep

there is a significant difference in problem solving ability between the two conditions: before and after losing one night of sleep

b)

the alternative hypothesis in symbols is:

h1: µ1≠ µ2

h1: µ1> µ2

h1: µd= 0

h1: µd≠ 0

h1: µd> 0

h1: md = 4.7

h1: md ≠ 4.7

h1: µd≤ 0

c)

the critical t-values are:

±2.064

±2.797

±1.711

±2.492

d)

the t-statistic is ?

( if it is a decimal number with two or more than two places, leave only two decimal places after the decimal point. do not round. )

e)

your decision is:

reject the null hypothesis and conclude that losing one night sleep did not affect problem solving

reject the null hypothesis and conclude that losing one night sleep significantly affected problem solving

fail to reject the null hypothesis and conclude that losing one night sleep did not affect problem solving

fail to reject the null hypothesis and conclude that losing one night sleep significantly affected problem solving

f)

compute estimated cohen’s d to measure the size of the effect

estimated cohen’s d is

note: if it is a decimal number with two or more than two places, leave only two decimal places after the decimal point. do not round.