Basic Applied Statistics 200
Solutions to Midterm 1
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- (iii) 1 categorical & 1 quantitative variable: use side-by-side
boxplots
- (ii) compare means and standard deviations
-
- (i) 2 categorical variables: bar graph
- (i) compare percentages
-
- taking CoQ10 or not
- (ii) categorical
- headaches (length & severity)
- (ii) patients before and after taking CoQ10
- (i) Was there a control group taking a placebo?
- 2 and (c)3
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- mean plus or minus 2 sds: 28 to 44
- z=(35-36)/4=-.25
- z=(50-36)/4=+3.5 so almost impossible
-
- (i) then (centered around higher numbers)
- (i) then has more spread
- (iv)neither is skewed
- 1.9 is middle of lower 15 values
-
- 20/30=.67
- 39/65=.60
- (iv) neither: they overlap, and are dependent because P(I) is
different from P(I|D)
- mutually exclusive (they received either drug or placebo, but not
both, so they do not overlap)
- 18,21,12,14
- 4/18+4/21+4/12+4/14=1.03
- (i) greater than .05 since chi-square is less than 3.84
- (ii) based on your answer to (g)
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- cigarettes exported
- 1.54 (the slope)
- (vi) -.83 (negative square root of .692)
- 969-1.54(525)=160.5 billion cigarettes
- 164-160.5=+3.5 billion cigarettes
- (ii) line affected by roles of explanatory and response but r is not
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