Question

There is some evidence suggesting that you are likely to improve your test score if you...

There is some evidence suggesting that you are likely to improve your test score if you rethink and change answers on a multiple-choice exam (Johnston, 1975). To examine this phenomenon, a teacher gave the same final exam to two sections of a psychology course. The students in one section were told to turn in their exams immediately after finishing, without changing any of their answers. In the other section, students were encouraged to reconsider each question and to change answers whenever they felt it was appropriate. Before the final exam, the teacher had matched 9 students in the first section with 9 students in the second section based on their midterm grades. For example, a student in the no-change section with an 89 on the midterm exam was matched with student in the change section who also had an 89 on the midterm. The difference between the two final exam grades for each matched pair was computed and the data showed that the students who were allowed to change answers scoring higher by an average of MD = 7 points with SS = 288. *PLEASE SHOW HOW TO DO WITHOUT CALCULATOR**

a. Do the data indicate a significant difference between the two conditions? Use a two-tailed test with α = .05.

b. Construct a 95% confidence interval to estimate the size of the population mean difference.

c. Write a sentence demonstrating how the results of the hypothesis test and the confidence interval would appear in a research report.

Homework Answers

Answer #1

Answer:

(a)

Given,

To indicate significant difference between two conditions

MD=7 , n=9, SS=288

standard deviation of difference=SD=sqrt(SS/(n-1))

= sqrt(288/8)

= 6

By using t-test and t = MD/(SD/sqrt(n))

Substitute the known values in expression

=7/(6/sqrt(9))

=3.5

Degree of freedom= (n-1)

=(9-1)

df = 8

critical t(0.05,8)=2.3 is less than calculated t=3.5 so there is significant difference in two condition.

(b)

To construct a 95% confidence interval to estimate the size of population mean difference

(1-alpha)*100% confidence interval for difference = difference±t(alpha/2,n-1)*sd/sqrt(n)

= difference ± t(.05/2, n-1)*sd/sqrt(n)

Substitute the values in above formula

= 7 ± 2.3*(6/sqrt(9)

= 7±4.6

= (2.4 , 11.6)

(c)

Hence we conclude that,

there is signigicant difference in in two conditions and the we are 95% confident that the difference of scores lies between 2.4 and 11.6.

Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
1.) One tailed test or two tailed test? You are performing a hypothesis test for the...
1.) One tailed test or two tailed test? You are performing a hypothesis test for the mean sample weight of your fellow Intro to Statistics students. For your null hypothesis , the hypothesized mean weight for the entire campus student body is 165. You have no reason to know for your alternative hypothesis whether the actual mean weight for the entire student campus body is more or less than 165. So you decide to make your alternative hypothesis as not...
Please note that for all problems in this course, the standard cut-off (alpha) for a test...
Please note that for all problems in this course, the standard cut-off (alpha) for a test of significance will be .05, and you always report the exact power unless SPSS output states p=.000 (you’d report p<.001). Also, remember when hand-calculating, always use TWO decimal places so that deductions in grading won’t be due to rounding differences. Problem Set 1: (22 pts) A teacher wanted to see if a new pedagogical approach was beneficial to students, and if the effects vary...
Delta airlines case study Global strategy. Describe the current global strategy and provide evidence about how...
Delta airlines case study Global strategy. Describe the current global strategy and provide evidence about how the firms resources incompetencies support the given pressures regarding costs and local responsiveness. Describe entry modes have they usually used, and whether they are appropriate for the given strategy. Any key issues in their global strategy? casestudy: Atlanta, June 17, 2014. Sea of Delta employees and their families swarmed between food trucks, amusement park booths, and entertainment venues that were scattered throughout what would...
There are two reflective essays from MED students during their third year internal medicine clerkship. One...
There are two reflective essays from MED students during their third year internal medicine clerkship. One student sees each connection to a patient as like the individual brush strokes of an artist and the other sees gratitude in a patient with an incurable illness and is moved to gratitude in her own life. (WORD COUNT 500) Reflect on both essays and then choose one and describe how the student grew from the experience. Then explain what you learned as a...