Can someone good at statistics explain this to me?

Post Reply New Topic

I have a terrible intro to stats professor. He goes over things way too quickly and its really hard to get the time to talk with him after class. My textbook also doesn't go over this as well. Anyway, if there is anyone on here that can explain these problems to me...I would greatly appreciate it:

After a hurricane, a disaster is divided into 200 equal grids and 30 are selected and every household in the grid is interviewed to help focus on relief efforts. Select the numbers of the first 5 grids that belong to the cluster sample: 16348 76938 90169 51392 55887 71015 09209 79157

The answer given is (at the bottom of the practice test emailed to me - 163, 169, 15, 92, 97

The second problem:

There are 750 freshman attending a university this fall. A researcher wishes to send questionnaires to a sample of 30 of them to complete regarding their drinking habits. Select the numbers of the first 5 freshman who belong to the simple random sample: 16348 76938 90169 51392 55887 71015 09209 79157

Answer: 163, 487, 693, 169, 513


I have absolutely no idea what this means and how to come up with these numbers. Could someone please explain this to me?

I think the listing of numbers as a series of five digit numbers is a bit of a red herring. We can rewrite the series using the same digits into a series of three digit numbers: 163 487 693 890 169 513 925 588 771 015 092 097 915 7.

In the first problem there are only 200 grids, so we can remove any of the above three digit numbers which are greater than 200, giving: 163 169 015 092 097, which is the answer

We can use the same method for the second problem, except we remove any number above 750 as there are only 750 freshman students

Caveat: I've never taken any kind of statistics course beyond high school, I'm just trying to work backwards from the answers.

It is funny because now I remember him actually using the same term to describe this - red herring.
Yes, this must be how to do them. I will confirm this with him after class Monday. I appreciate your help. Thanks a lot.

Ellingtonia's answer seems to be right and very well-worded, but I don't see how these problems are real statistics. I have never seen these "red herring" strings of numbers. It makes no sense what the point of that is. If you have a group of 750 freshmen, you randomly assign based on choosing numbers 1-750 randomly, whether it be out of a hat or from a computer program! The first five numbers to come up are the first five random selections. What in the world is this 16348 jargon?! Definitely ask your professor to clarify, and in my opinion, the most important thing you take away from this assignment is understanding WHY you randomly assign in a research project and HOW that is done when it comes time to do your own research.