Statistics (unit 3) - a few vocabulary words to remember (this is NOT all of them!!!)

Sampling method (how you sample the total population) :

(1) Simple random - think of a raffle. Put all the names in a hat and pull some out randomly.

(2) Stratified -

                 Split the population into groups: Say, all the 1A block classes at MHS

                 Then take A FEW RANDOM PEOPLE FROM EVERY GROUP.

(3) Cluster - also involves groups, but it's very different!

                 Split the population into groups: Say, all the 1A block classes at MHS

                Then choose a FEW GROUPS and take EVERY SINGLE PERSON in those groups.

(4) Systematic - think of the lunch line. Choose a random person to start, then take every 3rd person, every 10th person, or count by whatever set number to get your sample.

(5) Convenience - just what it sounds like. Take the easiest participants to get.

Observational vs. Experimental 

Observational is when you are only observing, not doing. You might be watching or listening in person, using a microphone or a camera, asking survey questions. But you are not changing what's happening (except maybe by accident, through biased survey questions or observer effect).

Experimental is when you set up a control group and a treatment group (or more than one) and you are actually doing something to see what happens as a result of a specific treatment.

Open vs. Closed 

If they have to choose from a selection of set answers (multiple choice, true/false, yes/no, "on a scale of 0 to 10"), it's closed. If they can say whatever they want, it's open.

Observer effect

When people change what they do or say because they're being watched.

Sampling bias

When you don't have a representative sample (only allowing men to vote, for instance), and this changes the results of the study.

Statistical bias

When a study is inaccurate because of problems with the tools or method - the scale for the potato chip study, or biased survey questions like "Isn't Marietta High School the best school in the state?"

Placebo - what's given in the place of the treatment (think: sugar pill in place of medicine).

Placebo effect - when even the placebo causes a change, because the participant believes there will be an effect.

Any other terms you're not sure about? Please ask us on the GroupMe!