Epidemiology: Errors and Confidence Intervals

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Questions and Answers

What is the main purpose of using stratified random sampling in the given example?

To select only women for the sample
To select only men for the sample
To ensure that the sample reflects the gender balance of the company (correct)
To ensure that the sample is more diverse

What is the proportion of women in the population according to the given data?

48.6%
28%
39%
51.4% (correct)

What is the advantage of stratified random sampling in terms of conclusions?

It allows for more diverse samples
It allows for more precise conclusions (correct)
It allows for faster data collection
It allows for only comparing population sub-groups

What is a disadvantage of stratified random sampling?

It is more complex and prone to errors (A) Signup and view all the answers

How many strata are used in the combined strata example?

3 (C) Signup and view all the answers

What is the proportion of people in the 0-14 age group in the population according to the given data?

16.1% (A) Signup and view all the answers

What is the primary cause of random error in epidemiological studies?

Chance and inherent sampling process (A) Signup and view all the answers

What is the effect of increasing the sample size on the 95% confidence interval?

The confidence interval becomes narrower (C) Signup and view all the answers

What is the primary difference between random error and systematic error?

Random error is introduced by chance, while systematic error is introduced by manmade actions (A) Signup and view all the answers

What is the result of selection bias in a study?

A biased sample, which almost always gives rise to biased estimates (D) Signup and view all the answers

What is the effect of increasing the sample size on chance bias in a study?

Chance bias decreases with the sample size (B) Signup and view all the answers

What is the purpose of a confidence interval in a study?

To indicate the level of uncertainty around the estimated measure (B) Signup and view all the answers

What is the basis of cluster sampling in a population?

Hierarchical structure of natural clusters (C) Signup and view all the answers

What is the purpose of taking a random sample of natural clusters in cluster sampling?

To select all individuals in the selected clusters (A) Signup and view all the answers

What is a potential disadvantage of cluster sampling?

Substantial differences between clusters (D) Signup and view all the answers

What is the main difference between cluster sampling and multi-stage sampling?

Number of sampling stages (A) Signup and view all the answers

What is the purpose of the first stage in multi-stage sampling?

Random selection of large clusters (D) Signup and view all the answers

What is a potential limitation of cluster sampling in terms of representativeness?

Selecting too few clusters (D) Signup and view all the answers

What is the purpose of multi-stage sampling?

To improve sample representativeness compared to simple random sampling (D) Signup and view all the answers

What can compromise the representativeness of a sample in multi-stage sampling?

Selecting too few clusters (C) Signup and view all the answers

What is the main advantage of systematic sampling compared to simple random sampling?

It is less costly and less time-consuming (A) Signup and view all the answers

What is an example of a systematic sampling method?

Selecting individuals based on their name starting with a certain letter (B) Signup and view all the answers

What is the first step in the procedure of systematic sampling?

List all individuals in the sampling frame in alphabetical order (D) Signup and view all the answers

What is the purpose of randomly selecting a starting point in systematic sampling?

To ensure that the sample is equivalent to a simple random sample (C) Signup and view all the answers

What is a major advantage of convenience sampling?

It is a cheap, fast, and convenient method. (B) Signup and view all the answers

Why is it always advisable to use probability sampling techniques when possible?

They provide a more representative sample and minimize selection bias. (A) Signup and view all the answers

What is a limitation of convenience sampling?

The sample is not representative of the population. (B) Signup and view all the answers

What factor should be considered when deciding on a sampling method?

The aim of the study, nature of the population, and other practical issues. (B) Signup and view all the answers

What is the ideal sampling method when there are no financial and time constraints?

Stratified random sampling. (C) Signup and view all the answers

What is assumed when non-random sampling techniques have been used?

Selection bias is operating to some extent. (D) Signup and view all the answers

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