Examples of using Post-stratification in English and their translations into Serbian
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It turns out that the bias of the post-stratification estimator is.
In fact, as we will see below,both approaches basically rely on the same estimation method: post-stratification.
Construct a situation where post-stratification can decrease the quality of estimates.
One common technique for utilizing auxiliary information is post-stratification.
For more on using post-stratification to adjust for nonresponse, see Smith(1991) and Gelman and Carlin(2002).
In particular, they used a more sophisticated form of the post-stratification I told you about.
Roughly, post-stratification helps correct for an imbalanced sample by bringing in auxiliary information about the sizes of the groups.
This massive sample size enabled them to form a huge number of post-stratification groups.
One way to think about it is that post-stratification is like approximating stratification after the data has already been collected.
Correct for the non-representativeness of your sample using post-stratification or some other technique.
Thus, as the number of groups used in post-stratification gets larger, the assumptions needed to support the method become more reasonable.
Correct for the nonrepresentativeness of your sample using post-stratification or some other technique.
Post-stratification requires that you know enough to put your respondents into groups and to know the proportion of the target population in each group.
Thus, the overall bias will be small if the bias in each post-stratification group is small.
In particular, they used post-stratification, a technique that is also widely used to adjust probability samples that have coverage errors and non-response.
Given this fact,researchers often want to create a huge number of groups for post-stratification.
But, there are three important points to keep in mind about post-stratification, all of which make it seem more promising.
Post-stratification is part of a more general family of techniques called calibration estimators, see Zhang(2000) for an article-length treatment and Särndal and Lundström(2005) for a book-length treatment.
There are two ways that I like to think about making the bias small in each post-stratification group.
(2015) uses a technique called multilevel regression and post-stratification(“Mr. P.”) that allows researchers to estimate group means even when there are many, many groups.
But, Chapter 3(Asking questions)shows that these problems are potentially addressable using post-stratification and sample matching.
They then adjusted for the non-representativeness of data using model-based post-stratification and compared their adjusted estimates with those from the probability-based GSS and Pew surveys.
If you can chop up the population into homogeneous groups such that the response propensities are the same for everyone in each group,then post-stratification will produce unbiased estimates.
They then adjust for the non-representativeness of data using model-based post-stratification(Mr. P), and compare the adjusted estimates with those estimated using probability-based GSS/Pew surveys.
In conclusion, this section has provided a model for probability sampling with non-response andshown the bias that nonresponse can introduce both without and with post-stratification adjustments.
It is worth learning a bit more about their approach because it builds intuition about post-stratification, and the particular version Wang and colleagues used is one of the most exciting approaches to weighting non-probability samples.
If there are only a small number of people in each group, then the estimates will be more uncertain, andin the extreme case where there is a group that has no respondents, then post-stratification completely breaks down.
In other words, thinking back to our example,using post-stratification will produce unbiased estimates if everyone in New York has the same probability of participating and everyone in Alaska has the same probability of participating and so on.
For example, one way in which you can use auxiliary information is post-stratification(recall eq. 3.5 from above).
One example of a design that can lead to unequal probabilities of inclusion is stratified sampling,which is important to understand because it is closely related to the estimation procedure called post-stratification.