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## High school statistics

### Course: High school statistics>Unit 5

Lesson 3: Sampling methods

# Systematic random sampling

In a systematic random sample, we arrange members of a population in some order, pick a random starting point, and select every member in a set interval. Created by Sal Khan.

## Want to join the conversation?

• Why is it important to randomly pick the first person? Can't we just simply pick every 100th person, for example? Why would that be biased?
• While that isn't super important we are just doing our best to get rid of all types of bias that could occur. In this case, we might be afraid that some time of bias could arise starting on intervals from the first "person" or "item".

Hope this helps. :-)
• , if the k=37, shouldn't we be surveying the next 37th person instead of the next 100th?
• If it was every 37th person, we would expect to survey roughly 269 people. Sal says we are surveying only a hundred, and as we know, 10,000/100=100. We would therefore have just the right amount if we survey every 100th person.

Hope this helps!
• Would systematic random sampling have bias like convenience since you are just at the front gate? Could you have two survey checkpoints were other people get surveyed?
• Good point! I suppose this example only refers to one entrance gate. Hopefully helped!