Basic Applied Statistics 200
Solutions to Midterm 1

1.  
   1. (iii) 1 categorical & 1 quantitative variable: use side-by-side boxplots
   2. (ii) compare means and standard deviations
2.  
   1. (i) 2 categorical variables: bar graph
   2. (i) compare percentages
3.  
   1. taking CoQ10 or not
   2. (ii) categorical
   3. headaches (length & severity)
   4. (ii) patients before and after taking CoQ10
   5. (i) Was there a control group taking a placebo?
4. 2 and (c)3
5.  
   1. mean plus or minus 2 sds: 28 to 44
   2. z=(35-36)/4=-.25
   3. z=(50-36)/4=+3.5 so almost impossible
6.  
   1. (i) then (centered around higher numbers)
   2. (i) then has more spread
   3. (iv)neither is skewed
   4. 1.9 is middle of lower 15 values
7.  
   1. 20/30=.67
   2. 39/65=.60
   3. (iv) neither: they overlap, and are dependent because P(I) is different from P(I|D)
   4. mutually exclusive (they received either drug or placebo, but not both, so they do not overlap)
   5. 18,21,12,14
   6. 4/18+4/21+4/12+4/14=1.03
   7. (i) greater than .05 since chi-square is less than 3.84
   8. (ii) based on your answer to (g)
8.  
   1. cigarettes exported
   2. 1.54 (the slope)
   3. (vi) -.83 (negative square root of .692)
   4. 969-1.54(525)=160.5 billion cigarettes
   5. 164-160.5=+3.5 billion cigarettes
   6. (ii) line affected by roles of explanatory and response but r is not

[ Home | Calendar | Assignments | Handouts ]