Statistics in a Modern World 800
Solutions to Exam 4
- (a) (-7,8) because it contains 0
- (b) (1,4) and (2,5) because they have the most overlap
-
- mean is population mean 3.5
- standard error is 1.7/square root of 25 = .34
- normal (or bell-shaped)
- mean plus or minus 1 standard error: between 3.16 and 3.84
- now standard error is 1.7/square root of 100 = .17: between
3.33 and 3.67
-
- standard error is square root of (.3)(.7)/933 = .015; 95% confidence
interval is sample proportion plus or minus 2 standard errors, or (.27,.33)
- no, because interval is way below .5
- (i) wider: dividing by larger sample gives larger margin of error
- (iii) inaccurate: the sample is biased
- (b) very small p-value provides very strong evidence, but it may be a
weak relationship
-
(c) sample must be random and large enough
-
- (ii) equal to 40
- (iii) greater than 40
- 20/square root of 1600 = .5
- (41-40)/.5 = 2
- probability of z greater than or equal to 2, same as probability of
z less than or equal to -2, .02 or .025
- yes because the p-value is small
- (i) yes because the sample size is large
-
- (iii) two-sample z test
- (iv) chi-squared test
- (i) z test about a proportion
- (ii) z test about a mean
- (a) one-sided test for a mean
- .08/2 = .04
- (b) combine into meta-analysis
- (b) do NOT tend to die earlier (that's why it's a paradox!)
- Extra Credit: smoking is the lurking (confounding) variable
[ Home
| Calendar
| Assignments
| Handouts
]
|