Starting in the 1970s, medical technology allowed babies with very low birth wei
ID: 3151895 • Letter: S
Question
Starting in the 1970s, medical technology allowed babies with very low birth weight (VLBW, less than 1500 grams, about 3.3 pounds) to survive without major handicaps. It was noticed that these children nonetheless had difficulties in school and as adults. A long-term study has followed 241 VLBW babies to age 20 years, along with a control group of 236 babies from the same population who had normal birth weight. Of the 128 women in the VLBW group, 37 said they had used illegal drugs; 50 of the 133 control group women had done so.
a.The test statistic for testing a null hypothesis of no difference with the VLBW women as group 1 is
z = (±.001) =?
and the P-value is (±.0001)=?
b.Is this difference between the two groups statistically significant at =0.05? Yes No
show step by step please
Explanation / Answer
a)
Formulating the hypotheses
Ho: p1 - p2 = 0
Ha: p1 - p2 =/= 0
Here, we see that pdo = 0 , the hypothesized population proportion difference.
Getting p1^ and p2^,
p1^ = x1/n1 = 37/128 = 0.2890625
p2 = x2/n2 = 50/133 = 0.37593985
Also, the standard error of the difference is
sd = sqrt[ p1 (1 - p1) / n1 + p2 (1 - p2) / n2] = 0.058047298
Thus,
z = [p1 - p2 - pdo]/sd = -1.496664846 [ANSWER, Z]
Also, the p value is
P = 0.134480488 [ANSWER, P VALUE]
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b)
As P > 0.05, we do not reject Ho.
Hence, NO, THIS DIFFERENCE IS NOT SIGNIFICANT. [ANSWER]
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Hi! I have seen some inconsistencies/contradictions in this problem, although I used the last part because they are what matters. If there are typo errors here, please resubmit this question together with the corrections. That way we can continue helping you! Thanks!
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