1. ## Sampling situations?

Hello everybody,

I want to work out the difference between two proportions, and my textbook tells me to first state the 'sampling situation' for the difference between the first proportion and the second? I'm just about to carry out a t-test.

My question is what does it mean by 'sampling situation'?

Does it just mean; P1-P2? Is this a sampling 'situation' or just a sampling parameter?

Thank you.

2. First off, feel free to indicate which textbook you are referring to. Second, it would do us all good if we knew the quote from the book to which you are referring. That context could help us see what you may not (and have left out stating). In such a review of the text, you might find the author specifying just what he means by 'sampling situation.' I have not seen this term before, but from a quick Google search it seems to be saying "define the sample with respect to its properties and how it relates to the larger population." In that case, so that the researcher can identify where bias can enter into the problem that distorts the sample values from the population to which we want to make inferences.

In the case of your statistical test, the parameter of interest is the difference in proportions. In this and other cases, the sampling situation, I believe, would be the specification of interesting facts: what are the sample sizes, what are the variances, what are the units of measure, etc. Basically, detail all the information about the situation. Usually when I approach such problems I start it with a column titled "Given" and I specify all the values. In this way, I can have a snapshot of all the important values in my calculations. Others I fill in as a summary table for what I calculated through the solution. All that information, it appears to me, is the "sampling situation."

3. Thank you Bryan, the textbook I'm taking about is called Chance Encounters a book by a New Zealand author for Auckland University. I have re-read the section a few times and I have watched a few of my recorded lectures online and what it seems to mean is the parameter being discussed as well as a little explanation of what the actually means. For example, because I'm woking out the difference between two proportions, the sampling situation would be P1-P2 = The difference between the proportion of (for e.g.) people who earned less than $12.50/hour (P1) and the proportion of people who earned more than$20.00/hour (P2).

It's just a way to say "state the parameter being discussed (with symbols and words)... I think, I could still be wrong. Math confuses me =(

I think I happen to be in the same statistics course as you, and I stumbled across this thread whole browsing the web. I hope you log on and read this before you have to hand in your assignment tomorrow.

The "sampling situation" of that particular question actually refers to the 3 types of situations when you have the difference of two proportions. Specifically, it's asking you to determine what type of sampling situation it is out of:

1. Two independent sample proportions.
2. One sample with multiple inclusive response categories.
3. One sample with multiple mutually exclusive response categories.

You will need this information in order to determine how to calculate the standard error when you do the t-test for the proportion difference.

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# situations of sampling

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