A seven-year medical research study reported that women...

A seven-year medical research study reported that women whose mothers took the drug DES during pregnancy were twice as likely to develop tissue abnormalities that might lead to cancer as were women whose mothers did not take the drug. a. This study involved the comparison of two populations. What were the populations? b. Do you suppose the data were obtained in a survey or an experiment? c. For the population of women whose mothers took the drug DES during pregnancy, a sample of 3980 women showed 63 developed tissue abnormalities that might lead to cancer. Provide a descriptive statistic that could be used to estimate the number of women out of 1000 in this population who have tissue abnormalities. d. For the population of women whose mothers did not take the drug DES during pregnancy, what is the estimate of the number of women out of 1000 who would be expected to have tissue abnormalities? e. Medical studies often use a relatively large sample (in this case, 3980 ). Why?

A seven-year medical research study reported that women whose mothers took the drug DES during pregnancy were twice as likely to develop tissue abnormalities that might lead
to cancer as were women whose mothers did not take the drug.
a. This study involved the comparison of two populations. What were the populations?
b. Do you suppose the data were obtained in a survey or an experiment?
c. For the population of women whose mothers took the drug DES during pregnancy, a sample of 3980 women showed 63 developed tissue abnormalities that might lead to cancer. Provide a descriptive statistic that could be used to estimate the number of women out of 1000 in this population who have tissue abnormalities.
d. For the population of women whose mothers did not take the drug DES during pregnancy, what is the estimate of the number of women out of 1000 who would be expected to have tissue abnormalities?
e. Medical studies often use a relatively large sample (in this case, 3980 ). Why?

Key Concepts

Population Comparison

This concept pertains to the identification and analysis of groups within a study. In many research studies, particularly in epidemiology, two or more groups are compared to determine differences in outcomes. The ability to clearly define and compare populations is essential in drawing valid conclusions about associations between exposure and outcome.

Observational Study Design

This concept involves studies where the researcher observes outcomes without modifying or controlling the exposure. In observational studies, such as those using surveys or historical data, the investigator simply collects data based on existing conditions. This is contrasted with experiments where treatments or interventions are assigned by the researcher.

Descriptive Statistics and Proportions

Descriptive statistics summarize and describe the features of a data set in a quantitative manner. Calculating proportions, such as the fraction of a sample exhibiting a particular outcome, is a key method to estimate how common a phenomenon is in a population. Proportions can be scaled (for example, per 1000 individuals) to provide an easily interpretable measure of prevalence.

Relative Risk

Relative risk is an epidemiological measure used to compare the probability of an event occurring in two different groups. It quantifies how much more (or less) likely an outcome is in one group compared to another, expressing the strength of an association between exposure and outcome.

Importance of Sample Size

A large sample size in studies, especially medical research, is critical for increasing the accuracy and precision of estimates. Large samples reduce random variation, improve the reliability of statistical tests, and help ensure that findings are more representative of the broader population. This improves confidence in the study's conclusions about the association between exposure and outcomes.

Transcript

00:01 Okay, so this question is about a study relating to taking a drug called des during pregnancy.

00:07 Part a says this study involved comparison of two populations, what were the populations? so they were looking at women who were pregnant with the drug des, and they were comparing them to women who were pregnant without the drug des.

00:24 So our two populations are just going to be pregnant women with des drug and pregnant women without des drug.

00:31 Part b says, do you suppose the data were obtained in a survey or an experiment? so it would not be ethical at all to have an experiment because that would involve forcing women to take des drug, even if they don't want to.

00:46 So it would definitely be a survey.

00:48 Again, because if it were an experiment, then they would have to randomly choose who takes des, even though some women obviously wouldn't want to take des.

00:58 Part c says, for the population of women whose mothers took des during pregnancy, a sample of 3 ,980 women showed that 63 developed tissue abnormalities that might lead to cancer, provide a descriptive statistic that could be used to estimate the number of women out of 1 ,000 in this population who would have tissue abnormalities.

01:20 So in this question, we just need to set up a proportion.

01:23 We know that 63 developed tissue abnormalities out of 3 ,980, and we want to find out how many would develop abnormalities out of a population of 1 ,000.

01:39 So we solve for x, we get about, well, we get 158 women out of a population of 1 ,000...

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