Can a sample be representative of the entire population?
The answer is: No. No sample is guaranteed to be representative of the entire population, although the risk of non-representative samples is reduced as sample size / total N gets larger.
How are populations divided according to their variables?
Population is divided into subgroups, called strata, according to some variable or variables in importance to the study Variables often used include: age, gender, ethnic origin, SES, diagnosis, geographic region, institution, or type of care
How to choose a representative sample for a survey?
Ensuring diversity of the sample is a tall order, as reaching some portions of the population and convincing them to participate in the survey could be difficult.
When do you need a representative sample for a study?
If you are conducting research on a specific population, you will want to make sure that your sample of that population is representative. If your sample is representative of your population, you will be able to confidently generalize the results of your study to that population.
Can a simple random sample be a representative sample?
Yes, a simple random sample has all the desired characteristics (mean and variance of statistics, etc.) of a representative sample of the population. But in practice, it is almost always virtually impossible to come up with a sample that is exactly a simple random sample.
What should be the sample size for a population study?
Once your population is large enough, your sample size doesn’t change very much anymore (e.g. for confidence level 95% and margin of error 5%, sample size for population = 1000 will be 278, for population 10,000 this is 370 and for 100,000 this is 383.
Which is the best Test to compare entire distributions?
Since you want to compare the entire distributions, I’d recommend the two sample Kolmogorov-Smirnov test. More information can be found here: You could test whether several statistics that are descriptive of a distribution are the same in the subsample and the remaining sample. For example you could conduct tests for: