Question

Use the following information for problems A-G.

A group of 44 women with gestational diabetes were assigned to one of two groups. Group 1 received standard care, and group 2 participated in group counseling visits. Researchers want to determine whether or not the birth weights of the infants of the mothers who participated in the group counseling visits were significantly different than the birth weights of mothers who received standard care at the α = 0.05 level. For your convenience, I have prepared an excel file with the birth weight in grams for both groups below. Use this data to answer questions 10-A.

What is the proper test to use?

two-sample t-test for dependent samples

none of the above

two-sample t-test for independent samples

one-sample z-test

B. What is the degrees of freedom for this study?

21

22

42

43

Question C.

What is the test statistic?

2.79

0.89

0.57

2.32

Question D

True or False, this finding is statistically significant.

True

False

Question E

Based on this information, the researcher should make the decision to ___________.

reject the null hypothesis

fail to reject the null hypothesis

Question F

What is the effect size?

0.0019

0.70

0.35

1.0

Question G

How would you interpret this effect size?

Medium

Strong

Weak

Group 1	Group 2
4350	4395
4225	4375
4650	4225
5400	3335
3850	3975
4450	4020
4375	3725
3950	3825
4525	4125
5200	4425
4800	4375
4275	4055
4175	4500
4230	4875
4650	3855
4300	3955
4650	4355
4725	3975
4325	4550
4225	4325
4350	4675
4575	4745

Answer 1

Data:        

n1 = 22       

n2 = 22       

x1-bar = 4466.14       

x2-bar = 4212.05       

s1 = 360.44       

s2 = 367.2       

Hypotheses:        

Ho: μ1 = μ2        

Ha: μ1 ≠ μ2        

Decision Rule:        

α = 0.05       

Degrees of freedom = 22 + 22 - 2 = 42      

Lower Critical t- score = -2.018081679       

Upper Critical t- score = 2.018081679       

Reject Ho if |t| > 2.018081679       

Test Statistic:        

Pooled SD, s = √[{(n1 - 1) s1^2 + (n2 - 1) s2^2} / (n1 + n2 - 2)] =   √(((22 - 1) * 360.44^2 + (22 - 1) * 367.2^2)/(22 + 22 -2)) =     363.8

SE = s * √{(1 /n1) + (1 /n2)} = 363.835700282421 * √((1/22) + (1/22)) = 109.7005912      

t = (x1-bar -x2-bar)/SE = 2.316213589       

p- value = 0.025498528       

Decision (in terms of the hypotheses):        

Since 2.316213589 > 2.018081679 we fail to reject Ho    

Conclusion (in terms of the problem):

There is sufficient evidence that the birth weights of the infants of the mothers who participated in the group counseling visits were significantly different than the birth weights of mothers who received standard care.

ANSWERS:

(A) Two-sample t-test for independent samples

(B) 42

(C) 2.32

(D) True

(E) Reject the null hypothesis

(F) 0.70

(G) Medium