Unit 4 Flashcards
what is a variable
something that can be categorized in a group
simple random sample (SRS)
1) give each ____a unique integer label from 1-whatever
2) use a random number generator to get _ unique number from 1-whatever
3) place half in one group and the other half in another group
4) the first group will get this treatment
5) the second group will get this treatment
6) compare both groups
convinience sample
biased, chosing people that are easy to reach
voluntary response sample
biased, chosing very one sided people
“rate us 5 stars on google for a giftcard”
voluntary response sample
blocks
group of expiremental units that are similar (common characteristics)
randomized block design
seperate subjects into blocks and randomly assign treatments within each block
matched pair design
-subjects are paired
-within each pair, randomly assign
simple random sample sequence
50 ppl - randomly assing — 25 ppl — 1st treatment \ compare
\ 25 ppl – 2nd treatment /
randomized blocking sequence
20 blue ppl–randomly assign– 10 ppl - 1 treatment \ compare
\ 10 ppl -2nd treatment /
30 red ppl—randomly assign–15 ppl— 1 treatment \ compare
\ 15 ppl –2 treatment /
then compare both
cofounding factor
can u conclude that taking the prep class will increase sat score increase?
no bc coufounding what if the seniors got more study time
observational study
just watching the ppl no treatment imposed
experimental study
treatment is exposed
shows causation
undercoverage versus overcoverage
like is ppl are less or more likley to be represented in a study
es- calling landlines
stratified random sample
-split population into multiple groups/ strata
(strata have common characteristics)
-then close a 1 or 2 random ppl from each group
