Question

1) Researchers in South Africa were interested in prevalence of HIV-related behaviors and infection in the population. They administered a survey of 500 men and women who came for health care at a hospital clinic in Johannesburg. At the same time, all subjects were tested for HIV status. Prevalence of HIV was higher in men than in women. Men were also more likely to use IV drugs and to engage in sex with multiple sex partners. What type of study design is this?

2)

Investigators interested in whether maternal-fetal sharing of HLA genes was associated with preeclampsia identified recent births from state birth certificate files. They selected all women whose birth certificate indicated preeclampsia in pregnancy and a random sample of women for whom preeclampsia was not indicated on the birth certificate. After confirming preeclampsia status in medical records, a total of 250 women with preeclampsia and a similar number of women without preeclampsia were enrolled. All women provided buccal cell samples from themselves and their babies for HLA-typing. Maternal-fetal sharing was more common among women with preeclampsia than women without preeclampsia. What type of study design is this?

Answer 1

Answer 1):

· In above question no. 1) it’s mentioned that researchers were interested in prevalence of HIV- related behaviors and infection in the Population and administered Survey of 500 men and women.

· So, first let’s define terms Population, Population Study and Survey in terms of Statistics before explaining Type of Study Design:

· In statistics, a population is a set of similar items or events which is of interest for some question or experiment.

· A statistical population can be a group of existing objects or a hypothetical and potentially infinite group of objects conceived as a generalization from experience.

· A population study is a study of a group of individuals taken from the general population who share a common characteristic, such as age, sex, or health condition. This group may be studied for different reasons, such as their response to a drug or risk of getting a disease.

· A survey is an investigation about the characteristics of a given population by means of collecting data from a sample of that population and estimating their characteristics through the systematic use of statistical methodology.

Next, let’s define Type of Study:

· It’s an Ecological (Population Based), Non-Experimental (Observational Study), Cross – Sectional Survey, Descriptive and Quantitative study.

Note:

Descriptive: A descriptive statistic is a summary statistic that quantitatively describes or summarizes features from a collection of information.

Quantitative study: that uses numerical analysis, in this case its comparison study between genders.

Cross – Sectional Survey: Assesses the prevalence of an outcome in a broad population at one point of time.

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Answer 2):

In above question no. 2) it’s mentioned that investigators interested in comparison between all women whose birth certificate indicated preeclampsia in pregnancy with a Random Sample of women for whom preeclampsia was not indicated on the birth certificate.

· So, first let’s define terms Population and Random Sample in terms of Statistics before explaining Type of Study Design:

· In statistics, a population is a set of similar items or events which is of interest for some question or experiment.

· A statistical population can be a group of existing objects or a hypothetical and potentially infinite group of objects conceived as a generalization from experience.

· In statistics, a simple random sample is a subset of individuals (a sample) chosen from a larger set (a population).

· Each individual is chosen randomly and entirely by chance, such that each individual has the same probability of being chosen at any stage during the sampling process, and each subset of k individuals has the same probability of being chosen for the sample as any other subset of k individuals.

Next, let’s define Type of Study:

It's a Case Control Study, Non-Experimental (Observational Study), Sample, Descriptive and Quantitative study.

Note:

Case Control Study: Compares histories of a group of people with a condition to a group of people without.

Quantitative study: that uses numerical analysis, in this case its comparison study between sample group of 250 women with preeclampsia v/s women without preeclampsia.