EXAM!-Stratified Sampling and Random Stratified sample - Whats the difference?

[kazzacae]

Hey guys as the title says
what's the difference between Stratified Sampling and Random Stratified sample? does anyone have an example?I am struggling to understand the difference, if there is one.
Cheers

[minilunchbox]

Stratified sampling refers to the procedure of choosing participants from a sample by first dividing the population into distinct 'strata' (groups) such as year levels or social-economic status and then selecting a proportional amount of participants from each strata/group.

A random stratified sample is referring to an actual sample drawn from a population using stratified sampling (see above).

[kazzacae]

thanks but that doesn't really answer my question.
Is it even possible to have a stratified sample that is not random?

[coolhat]

basically Stratified sampling involves dividing the population to be sampled into distinct subgroups, then selecting a separate sample from each subgroup, in the same proportions as they appear in the target population

while stratified random sampling is where lists of all the people within each stratum are first obtained and random samples of proportionate size are drawn from within each of the strata.

hope that helps

[Spreadbury]

basically Stratified sampling involves dividing the population to be sampled into distinct subgroups, then selecting a separate sample from each subgroup, in the same proportions as they appear in the target population

while stratified random sampling is where lists of all the people within each stratum are first obtained and random samples of proportionate size are drawn from within each of the strata.

hope that helps

so stratified samples are biased?

[coolhat]

i guess

[Boots]

so would you say that the random stratified sampling technique is more effective ?

in the normal stratified sampling, how are the people from each group selected? If its not random than what could it be?

[Boots]

And what are the advantages and disadvantages of stratified and random sampling? Its in the study design i just checked.

[Glockmeister]

Stratified Sampling

Advantages
- You can get strata, that is variables such as different ages that you wouldn't be able to elute otherwise. That is you may be able to pick up differences in different age groups, cultures etc. that you may be not get in a normal random sampling.

Disadvantages
- Time and Money.

Random Sample
Advantages
- Better likelihood for getting a representative sample.

Disadvantages
- May have an overrepresentation of certain groups.

[Chromeo33]

basically Stratified sampling involves dividing the population to be sampled into distinct subgroups, then selecting a separate sample from each subgroup, in the same proportions as they appear in the target population

while stratified random sampling is where lists of all the people within each stratum are first obtained and random samples of proportionate size are drawn from within each of the strata.

hope that helps

so stratified samples are biased?

Wouldn't say so.
They're more representative of the population in which they occur in actualy reality, so how can they be bias?

[Boots]

It is bias in terms of how participants are selected from each strata. Random stratified sampling eliminates this