Study Guide

Designing a Study

Designing a Study

There's a high probability (see what we did there?) that at some point in your probability/statistics unit, your teacher will ask you to do a data-gathering statistics project. Don't worry, we can help!

These kinds of projects always follow more or less the same pattern. Here are the steps you need to know:

  1. Ask a question
  2. Form a hypothesis
  3. Collect your data
  4. Analyze your data
  5. Display your data
  6. Make a conclusion

What Makes a Good Question?

To start, you need to have a good "theme question" to ask. Pick something that interests you. You may need to ask follow-up questions to fully develop your project. You also need to know what kind of data to collect: for example, should it be numerical data or can it be data that has answers given in words? Do you need both?

Examples of good questions for a statistical study:
          a) Do the political views of parents influence the political views of students at Shmoople Hills High School?
         b) Do 8th graders in my school need less homework each night?

Why these are good questions:
       a) They are interesting.
       b) They’re specific about a targeted audience.

Examples of not-so-good questions for a statistical study:
        a) Are girls or boys taller?
        b) Is swimming more popular than ice hockey?

Why these are not-so-good:
       a) If you don’t put a boundary around the audience you’re measuring, things get a lot more complicated – are you trying to make a statement about all the girls and boys in the world? Phew, that could get tiring.
      b) In general, simple popularity contests don’t reveal interesting correlations for statistical studies.

After you pick your topic, you need to design the specific questions you will ask. Good questions are unbiased, meaning that they don't try to influence the person being asked. Let's say that you want to try to cut down on the amount of homework your teachers assign and ask the following questions:
        a) On average, how much time do you spend each night on homework?
        b) Many kids are concerned about not having enough free time. Do you agree?

Which question is biased, a or b? If you answered b, you are probably awake and paying attention. Question b is leading the interviewee to agree with you. The best questions are concise, specific, direct, and neutral (non-leading).