stats pt 1

Shargrodosky, Curhan, Curhan, and Eavey(2010)studied whether hearing loss among teens has increased. The researchers compared a random sample of 2928 teens from a 1994 study to a random sample of 1771 teens from a 2006 study . In the 1994 study, 480 teens had hearing loss while in the 2006 study, 333 had hearing loss. The researchers are trying to estimate the difference in the two populations, LaTeX: pi_{2006} - pi_{1994}
π 2006 π 1994
. The researchers tested the hypotheses

LaTeX: H_0: pi_{2006} - pi_{1994}=0 text{ vs } H_A: pi_{2006} - pi_{1994} neq 0
H 0 : π 2006 π 1994 = 0 vs H A : π 2006 π 1994 0

They calculated a p-value=0.0343 and Z=2.12 and designated LaTeX: alpha = 0.05
α = 0.05
. Answer the following questions using this information.

Identify the explanatory and the response variable.

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Select all of the following statements that are correct.

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A clinical study conducted in the early 1990s recruited 324 pregnant women who were HIV-positive. The researchers believe that the pregnant women taking AZT will have fewer babies born HIV-positive. Of the 164 women who were randomly assigned to use the experimental (at the time) drug AZT, 13 had HIV-positive babies. Of the 160 women who were randomly assigned to receive a placebo, 40 had HIV-positive babies. The data has been summarized in the following table. Use this information to answer the following questions.

AZT mothers Placebo mothers ROW TOTAL
HIV-positive baby 13 40 53
not HIV-positive baby 151 120 271
COLUMN TOTAL 164 160 n = 321

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Is this study an observational study or an experiment?

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Identify all of the parameters for this study.

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Write out the null and alternative hypotheses for this study.

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Are the validity conditions satisfied for this study?

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A random selection of married couples from Joliet, IL were asked to state how much TV they watched in the week of June 2 to June 8, 2019. The researchers are trying to determine if there is any difference in the TV watching habits between married couples. A matched pairs design was used and for each couple the difference (Wife – Husband) was calculated for each couple. The sample summary statistics and boxplots of the data are presented below.

HusbandWivesSummaryStatisticsTVHours.PNGHusbandWivesBoxplotsTVHours.PNG

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State the null and alternative hypotheses.

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