Midterm Flashcards
Which statements concerning residuals is true?
Sum is 0
Plot is useful for looking at the LSRL
value = observed - predicted
If linear than no pattern
The fraction of the variation in the values of y that is explained by the LSRL
The square of the correlation coefficient
LSRL
Line that makes the sum of the squares of the vertical distances of the data points from the line as small as possible
What is true of the correlation coefficient r
It does not change if either all the X-Data or all the y-Data are multiplied by a constant
What is true of LSRL
No more than 50% of residuals value will be +
Always pass the coordinate of the means of the expl and resp variable
Slope is change in response var that would be predicted by a unit change in the expl var
Always pass through all data points if r=+/- 1
Statistical inference
Answers to what degree of confidence we feel the experiment shows cause and effect
Census
Entire population is included in a survey
Simple random sample
Sample chosen so that everyone has an equal chance of getting selected
Stratified random sample
Divide population into separate groups with similarities and choosing from these subgroups by random method to get sample
Strata
Subgroup of an entire population with some similar characteristics that lumps them into this group
Cluster sampling
Divide population into subgroups, choose randomly what groups will be used, then all members of picked subgroups will be used
Confounding (lurking) variable
Extraneous factor
Matched pairs design
Compare two treatments and block members of experimental units into couples and then assign one member of each couple to each treatment
Block design
Create groups that are similar then make sure all treatments are tried in each group
Probability model
Simulation based off knowledge of all possible outcomes and the chance of these outcomes
