Testing of hypothesis using STAT DISK

1.In a randomized controlled trial in Kenya, insecticide treated bednets were tested as a way to reduce malaria. Among 343 infants who used the bednets, 15 developed malaria. Among 294 infants not using bednets, 27 developed malaria. Use a 0.01 significance level to test the claim that the incidence of malaria is lower for infants who use the bednets appear to be effective.

nets no nets
Malaria
No malaria
Total:

alpha = 0.01

p nets =

p nonets =

Claim:

H0 :

H1 :

Critical Value:

Test Statistic:

P-value associated with the test statistic:

Decision:

Conclusion: (Do the bednets appear to be effective?)

2.A study was conducted to assess the effects that occur when children are exposed to cocaine before birth. Children were tested at age 4 for object assembly skill, which was described as a task requiring visual spatial skills related to mathematical competence. The 190 children born to cocaine users had a mean of 7.3 and a standard deviation of 3.0 The 186 children not exposed to cocaine had a mean score of 8.2 with a standard deviation of 3.0 Use a 0.05 significance level to test the claim that prenatal cocaine exposure is associated with lower scores of four year old children on the test of object assembly.

Directions specify to NOT assume equal population standard deviations.
Prenatal Exposure (population 1)
n = s = x=

No Prenatal Exposure (population 2)
n = s = x=

alpha = 0.05
Claim:

H0 :

H1 :

Critical Values:

Test Statistic:

P-value associated with the test statistic:

Decision:

Conclusion:

3.Many students have had the unpleasant experience of panicking on a test because the first question was exceptionally difficult. The arrangement of test items was studied for its effect on anxiety which most of us call panic or blanking out. Is there sufficient evidence to support the claim that the arrangement of the test items has an effect on the score?

Questions arranged from easy to difficult
24.64 39.29 16.32 32.83 28.02
33.31 20.60 21.13 26.69 28.90
26.43 24.23 7.10 32.86 21.06
28.89 28.71 31.73 30.02 21.96
25.49 38.81 27.85 30.29 30.72

Questions arranged from difficult to easy
33.62 34.02 26.63 30.26
35.91 26.68 29.49 35.32
27.24 32.34 29.34 33.53
27.62 42.91 30.20 32.54

Easy to Difficult Arrangement:
n = x= s =
Difficult to Easy Arrangement:
n = x= s =

Use alpha = 0.05
Claim:

H0 :

H1 :

Critical Values:

Test Statistic:

P-value associated with the test statistic:

Decision:

Conclusion:

4(a)As part of the National Health Survey, self reported heights and measured heights were obtained for males aged 12 -16. Listed below are sample results. Is there sufficient evidence to support the claim that there is a difference between self reported heights and measured heights of males age 12 -16? Use a 0.05 significance level.

Reported height 68 71 63 70 71 60 65 64 54 63 66 72
Measured height 67.9 69.9 64.9 68.3 70.3 60.6 64.5 67.0 55.6 74.2 65.0 70.8

d= sd = alpha= 0.05
Claim:

H0 :

H1 :

Critical Values:

Test Statistic:

P-value associated with the test statistic:

Decision:

Conclusion:

4(b) Using the chart from question 4(a) construct a 95% confidence interval estimate of the mean difference between reported heights and measured heights. Interpret the resulting confidence interval and comment on the implications of whether the confidence interval limits contain zero.

95% Confidence Interval (use the correct notation):

Comment on the implications of whether the confidence interval limits contain zero:

6. Many students have had the unpleasant experience of panicking on a test because the first question was exceptionally difficult. The arrangement of test items was studied for its effect on anxiety. Sample values consisting of measures of debilitating test anxiety are obtained for a group of subjects with test questions arranged from easy to difficult and another group with test questions arranged from difficult to easy. Here are the summary statistics: Easy to difficult group: n = 25, x =27.115, s2 = 47.020; difficult to easy group; n = 16, x= 31.728, s2 = 18.150.

Questions arranged from easy to difficult
24.64 39.29 16.32 32.83 28.02
33.31 20.60 21.13 26.69 28.90
26.43 24.23 7.10 32.86 21.06
28.89 28.71 31.73 30.02 21.96
25.49 38.81 27.85 30.29 30.72

Questions arranged from difficult to easy
33.62 34.02 26.63 30.26
35.91 26.68 29.49 35.32
27.24 32.34 29.34 33.53
27.62 42.91 30.20 32.54

Include Statdisk image or printout
Claim:

H0 :

H1 :

Critical Values:

Test Statistic:

P-value associated with the test statistic:

Decision:

Conclusion: