1. In the following observational studies, describe changes that could be made t
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Question
1. In the following observational studies, describe changes that could be made to the data collection process that would result in an experiment rather than an observation study. Also, offer suggestions about unseen biases or lurking variables that my be present in the studies as they are describe here.
a. In a sample of 50 members of a local health club you find that 12 of these members meet weekly with a physical fitness trainer and that the average body mass index (BMI) of these 12 members is less than the average BMI of the other 38 club members in your sample.
b. In a sample of 12 bank tellers at a local branch office, the 7 tellers who have completed the advanced training program offered by the bank have a lower average error rate in the processing of transactions than the remaining 5 tellers.
Explanation / Answer
p1=12/50=0.24 and p2=38/50=0.76
Here the null hypothesis H0; P1<P2 against the alternatives H1: P1P2
One-Sample T
Test of mu = 0.76 vs > 0.76
95% Lower
N Mean StDev SE Mean Bound T P
50 0.2400 0.4300 0.0608 0.1380 -8.55 1.000
From this result we see that t=-8.55 and p value corresponding to t is 0.99 which is greater than 0.05 at 5% level of significance therefore we accept the null hypothesis.
Hence the average body mass index (BMI) of these 12 members is less than the average BMI of the other 38 club members
b) Here n=12.
p= 7/12=0.58
and p2=5/12=0.42
Here the null hypothesis H0:P <0.42 against the alternative P>=0.42
Test of p = 0.42 vs p > 0.42
95% Lower Exact
Sample X N Sample p Bound P-Value
1 7 12 0.583333 0.315238 0.196
From this result we say that p value corresponding to T is 0.196 which is greater than 0.05 at 5% level of significance therefore we accept the null hypothesis.
Hence the 7 tellers who have completed the advanced training program offered by the bank have average error rate in the processing of transactions than the remaining 5 tellers
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