Basic Applied Statistics 200
Solutions to Practice Midterm 1
-
- (i) 2 categorical variables: use bar graph
- (i) compare percentages
-
- (iv) 2 quantitative variables: scatterplot
- (iv) report correlation
-
- mean plus or minus 3 sds: 1.1 to 1.7
- z=(1.25-1.4)/=-1.5
-
- (ii) firearms (centered around higher numbers)
- (iii) both about the same
- (iii) both about the same
- 21 is middle of upper 5 values
-
- 150/360=
- 90/240=
- (iv) neither: they overlap, and are dependent because P(B) is
different from P(B|F)
- mutually exclusive (and dependent, because knowing someone ate breakfast
tells us the probability of not eating breakfast
is zero)
- 100, 140, 50, 70
- 1+.7+2+1.4=5.1
- (i) less than .05 since chi-square is greater than 3.84
- (ii) because the percentage eating breakfast is significantly less
for females, but we cannot jump to conclusions about the reason for this
-
- size
- 15.9 (the slope)
- (vi) .83 (positive square root of .687)
- -141+15.9(40)=495 thousand dollars
- 523-495=+28 thousand dollars
- 30
-
- (ii) and (iii) B and C because no treatment is imposed
- (ii) B depends on memory
- (iii) C because they are aware of the study as they perform
their activities of the day, including watching TV and eating
- (i) A because the subjects are not at home
- (ii)categorical: whether they are watching TV or not
-
- (i) year
- (iii) exposure to black and white movies, TV, and photos
- don't know/not sure
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