30 Questions
What is the main purpose of using stratified random sampling in the given example?
To ensure that the sample reflects the gender balance of the company
What is the proportion of women in the population according to the given data?
51.4%
What is the advantage of stratified random sampling in terms of conclusions?
It allows for more precise conclusions
What is a disadvantage of stratified random sampling?
It is more complex and prone to errors
How many strata are used in the combined strata example?
3
What is the proportion of people in the 0-14 age group in the population according to the given data?
16.1%
What is the primary cause of random error in epidemiological studies?
Chance and inherent sampling process
What is the effect of increasing the sample size on the 95% confidence interval?
The confidence interval becomes narrower
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
What is the result of selection bias in a study?
A biased sample, which almost always gives rise to biased estimates
What is the effect of increasing the sample size on chance bias in a study?
Chance bias decreases with the sample size
What is the purpose of a confidence interval in a study?
To indicate the level of uncertainty around the estimated measure
What is the basis of cluster sampling in a population?
Hierarchical structure of natural clusters
What is the purpose of taking a random sample of natural clusters in cluster sampling?
To select all individuals in the selected clusters
What is a potential disadvantage of cluster sampling?
Substantial differences between clusters
What is the main difference between cluster sampling and multi-stage sampling?
Number of sampling stages
What is the purpose of the first stage in multi-stage sampling?
Random selection of large clusters
What is a potential limitation of cluster sampling in terms of representativeness?
Selecting too few clusters
What is the purpose of multi-stage sampling?
To improve sample representativeness compared to simple random sampling
What can compromise the representativeness of a sample in multi-stage sampling?
Selecting too few clusters
What is the main advantage of systematic sampling compared to simple random sampling?
It is less costly and less time-consuming
What is an example of a systematic sampling method?
Selecting individuals based on their name starting with a certain letter
What is the first step in the procedure of systematic sampling?
List all individuals in the sampling frame in alphabetical order
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
What is a major advantage of convenience sampling?
It is a cheap, fast, and convenient method.
Why is it always advisable to use probability sampling techniques when possible?
They provide a more representative sample and minimize selection bias.
What is a limitation of convenience sampling?
The sample is not representative of the population.
What factor should be considered when deciding on a sampling method?
The aim of the study, nature of the population, and other practical issues.
What is the ideal sampling method when there are no financial and time constraints?
Stratified random sampling.
What is assumed when non-random sampling techniques have been used?
Selection bias is operating to some extent.
Test your understanding of errors in epidemiological studies, including chance bias and how it relates to sample size. Learn how confidence intervals indicate the level of uncertainty around estimated measures and what a 95% confidence interval means.
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