B 2 the prospective employee gets drug tested and the

(b)
(2)
The prospective employee gets drug tested, and the test comes out to be positive. What is
the posterior probability that they are actually a user for the drug? (Answer this question based
on the tree)
(c)
(1)
When the employee finds out that they tested positive, they refuse the test results, and say
they would like to be tested again. What is the new prior probability you should use for this
employee being a user of this drug?
(d)
(1)
The employee tests positive again in the second test. Should the new probability of them
actually being a user of this drug be higher or lower than what you calculated before, or the same?
10

6. (5 pts) City council survey. Match the following
A city council has requested a household survey be conducted in a suburban area of their city. The
area is broken into many distinct and unique neighborhoods, some including large homes, some with
only apartments, and others a diverse mixture of housing structures. Match the appropriate sampling
methods.
(1) Divide the city into neighborhoods, randomly sample 10 neighborhoods, and sample all house-
holds from those neighborhoods.
(2) Sample the 200 households closest to the city council offices.
(3) Randomly sample 50 households from the city.
(4) Divide the city into neighborhoods, randomly sample 10 neighborhoods, and then randomly sam-
ple 20 households from those neighborhoods.
(5) Divide the city into neighborhoods, and sample 20 households from each neighborhood.
(a) Simple random sampling.
(b) Stratified sampling.
(c) Cluster sampling. .
(d) Multi-stage sampling.
(e) Convenience sampling.
Fill in the blanks - 2 points each (Total 10 points)
For questions 7 to 11, fill in the blanks. Write legibly.
7.
(2)
The difference between an observed and predicted response is
called the .
8.
(2)
All else equal, a 99% confidence interval is than a 90% confidence interval.
9.
(2)
An extraneous variable that is related to the explanatory and response variables and that prevents
us from deducing causal relationships based on observational studies is called a .
10.
(2)
The probability of rejecting the null hypothesis when the null hypothesis is false is
called the .
11

11.
(2)
The theorem that describes the sampling distribution of a sample statistic is called
the .
12