A biologist is interested in the relationship between susceptibility to certain carcinogens and gender. To test this hypothesis, a simple random sample of 1200 male rats is selected while, independently, a simple random sample of 1200 female rats is selected. The three carcinogens are the microbial carcinogen aflatoxin B₁ and two viral carcinogens, hepatitis B and human papillomavirus (HPV) , which have both been found to cause cancer in humans. The rats were randomly assigned to receive one of the three carcinogens, with each carcinogen being given to 400 rats of each gender. The following table summarizes the number of rats of each gender that developed a tumor under a given treatment:
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$\begin{array} { | l | c | c | } \hline & { \text { Gender } } \\\hline { \text { Carcinogen } } & \text { Male } & \text { Female } \\\hline \text { Aflatoxin } B _ { 1 } & 96 & 295 \\\hline \text { Hepatitis B } & 32 & 45 \\\hline \text { HPV } & 94 & 40 \\\hline\end{array}$ What is the best description of the sampling design used to obtain the rats for the study?

Question

A biologist is interested in the relationship between susceptibility to certain carcinogens and gender. To test this hypothesis, a simple random sample of 1200 male rats is selected while, independently, a simple random sample of 1200 female rats is selected. The three carcinogens are the microbial carcinogen aflatoxin B₁ and two viral carcinogens, hepatitis B and human papillomavirus (HPV) , which have both been found to cause cancer in humans. The rats were randomly assigned to receive one of the three carcinogens, with each carcinogen being given to 400 rats of each gender. The following table summarizes the number of rats of each gender that developed a tumor under a given treatment:
?

\begin{array} { | l | c | c | } \hline & { \text { Gender } } \\\hline { \text { Carcinogen } } & \text { Male } & \text { Female } \\\hline \text { Aflatoxin } B _ { 1 } & 96 & 295 \\\hline \text { Hepatitis B } & 32 & 45 \\\hline \text { HPV } & 94 & 40 \\\hline\end{array}

What is the best description of the sampling design used to obtain the rats for the study?

Quizplus · Accepted Answer

The sampling design is stratified sampling because the population was divided into two strata (male and female rats) before the samples were randomly selected.

A Biologist Is Interested in the Relationship Between Susceptibility to Certain