# PROBLEMS

Document Sample

```					PROBLEMS:

CHAPTER 2
1. The largest health care organization in North Texas has decided to donate money
to area universities to foster and encourage these universities to incorporate more
health care topics into their curriculum. It was suggested that the allocation of
this money should be based on universities attended by their employees. A
survey of 300 professional employees resulted in 200 who attended local
universities. The universities not considered local were ignored. This data can be
found in “Excel Data”, Tab C2 – Prob 1. Summarize this data for a brief
presentation to management, using whatever statistical tools are appropriate.
2. The administrator of a local hospital is constantly having patients complain about
the poor quality of their health care during their stay in the hospital. In order to
care, the administrator randomly select 160 recent patients and has her staff call
each one on the phone and solicit their opinion as to the quality of care they
received. Two patients refused to answer resulting in 158 responses. This data
can be found in “Excel Data”, Tab C2 – Prob 2. Summarize this data for the
administrator using whatever statistical tools are appropriate.
3. A common complaint of patients is the time they have to wait “beyond their
appointment time” before they see their doctor. In order to study the extent of this
problem, the doctor asked his staff to randomly pull 300 patient files and calculate
the time between their appointment time and when they actually got to see the
doctor [fortunately these two times were captured for each patient]. This data can
be found in “Excel Data”, Tab C2 – Prob 3. Summarize this data for the
administrator using whatever statistical tools are appropriate. What would you
suggest to the doctor after reviewing your results.
4. Blue Cross suspects that some hospitals intentionally keep patients extra days to
pad the bill. The Blue Cross statistician selected a very common and stable
operation, performed very frequently by all hospitals, and pulls the number of
days a patient stayed in the hospital. This data can be found in “Excel Data”, Tab
C2 – Prob 4. Summarize this data for the administrator using whatever statistical
tools are appropriate. Be sure to include a cross-tab.
5. In order to plan effectively, it is important that the anesthesiologist be able to
estimate how long it will take for the drug to put the patient to sleep. It is known
that this length of time increases with the age of the patient. In order to study this
problem, a local surgical hospital agreed to collect this data for one week. This
data can be found in “Excel Data”, Tab C2 – Prob 5. Summarize this data for the
administrator using whatever statistical tools are appropriate. Be sure to include a
scatter plot.

Chapter 4 (and 3)
1. For the following data, identify whether or not they are 1. categorical [nominal
or ordinal], or 2. interval/numerical [discrete or continuous] Give examples of
possible values for each random variable. [Example: number of children living in
a given home – “interval data [discrete], (0, 1, 2, 3, …)”
a. marital status
b. number of students who drop this statistics course.
c. time student spends studying for their first statistics test.
d. the weight loss over the first week of a “fad” diet
e. the amount owed on a credit card (explain you answer)
f. the part on a new automobile that breaks during the first year of ownership
2. A random sample of grade point averages for 20 students resulted in the following
data. [data is sorted for you from smallest to largest]
[1.84, 1.94, 2.15, 2.22, 2.37, 2.76, 2.82, 2.89, 2.94, 2.96. 2.99, 3.05, 3.11, 3.24,
3.26, 3,29, 3.33, 3.54, 3.58, 3.79]
a. use 5 class intervals (cells) to describe this data in a frequency
distribution, and relative frequency distribution.

Relative
Class Interval        Frequency        Frequency

b. on the following graph, draw a frequency histogram. (show all relevant
information on graph including relative frequency)
Relative Frequency
Frequency

3. Data from the last statistics course was collected on the number of hours each
student studied and their grade on the final resulting in

Number Hours
Studied    30        22        40
Grade on Final   85        70        65

Plot a scatter diagram for this data showing the relationship between the two
variables. Show all relevant information on the graph (this means it should look just
like one you would put in a report prepared for President Bush).
4. The number of sick days due to colds and flu last year at UTA was recorded for 5
faculty resulting in [ 5, 4, 0, 6, 0 ]. Calculate the following statistics
a. mean
b. median
c. variance
d. standard deviation
5. The mean grade point average (gpa) for UTA students is 2.5 with a standard deviation
of 0.5
a. If the histogram for gpa’s is approximately mounded, what percent of the
gpa’s would you expect between 1.5 and 3.5?
b. If the histogram for gpa’s is approximately mounded, what percent of the
gpa’s would you expect greater than 3.5?
c. If the histogram for gpa’s is NOT mounded, what percent of the gpa’s
would you expect between 1.5 and 3.5?

CHAPTER 6
1. Bayes's Problem: Six percent of black americans are carriers of sickle cell anemia. a
new test to detect the carrier gives a positive indication 98% of the time when the
individual is a carrier and gives a negative indication 94% of the time when the
individual is not a carrier. A black american is selected at random from this population,
given the test and reacts positively. What is the probability that he is a carrier.

2. Bayes's Problem: From past records it was determined that 20% of all hospital bills
contain an error or errors. It was decided to hire a university intern to 100% inspect all
records to identify incorrect ones. These then would be corrected by hospital
personnel. While training the intern, it was determined that he misclassifies bills
containing errors 10% of the time [if a bill contains an error, there is a 10% chance that
he will not detect this error]. Also he misclassifies bills containing no error 5% of the
time [if a bill contains no error, there is a 5% chance that he will classify it as containing
an error]. If the hospital data base for last year contains 100,000 bills [80,000 with no
errors and 20,000 with errors], (a) how many of these bills would the intern classify as
containing an error, (b) of these, how many actually did not have an error.

CHAPTER 7
1. Binomial Distribution: For a particular couple, both carrying a gene for Osteogenesis
Imperfecta, the probability that they will have a child with this disorder is 1/4. This
couple wants to have 3 children. (a) What is the probability that none of their children
will have this disorder? (b)What is the probability that they will have at least one child
with this disorder?
2. Poisson Distribution: Weekly inspections of the operating room for infectious
bugs resulting in the quality inspector finding an average of 3.2 bugs each week.
Microbiologist have determined that the distribution of the number of bugs found
each week follows a poisson distribution [in this case with a mean of 3.2]. (a) what is
the probability that you find 2 bugs next week? (2) what is the probability that you
find more than 5 bugs next week? (3) what is the probability that you find more
than 12 bugs next week? (4) if you did find 13 bugs next week, what would you

CHAPTER 8
1. Normal Distribution: Patients tend to lose weight during hospital stays. Over the
years it was determined that the weight loss for a 5 day hospital stay was approximately
normal with a mean of 5 pounds and standard deviation 5 pounds. (a) What is the
probability that a randomly selected patient will not lose any weight? (b) What is the
probability that a patient will lose over 3.5 pounds? (c) What is the probability that a
patient will lose exactly 4 pounds? (d) What is the probability that a patient will lose
over 10 pounds? (e) If a patient did lose 10 pounds, what would you recommend?

CHAPTER 9
1. Distribution of Sum of Random Variables: The number of minutes a nurse spends,
during a 8 hour shift, with each patient in their ward is normally distributed with a mean
of 20 minutes and standard deviation 5 minutes [assume the time nurses spend with
patients is a function of the needs of the patient]. If the hospital budgets for each nurse
to serve 22 patients [22 patients are assigned to each nurse], what is the mean and
standard deviation of the total time the nurse spends on treating her 22 patients? What
is the probability that the nurse has to work beyond her 8 hour shift during a randomly
selected day?

CHAPTER 10

CHAPTER 11

CHAPTER 12

CHAPTER 13
1. Difference in Means: A HMO has established a rule that allows billing for the average
direct nursing cost per patient in the respiratory and cardiac intensive care units of
hospitals [define direct nursing cost as the actual costs based on the time a nurse
attends a given patient]. Unfortunately this data does not exist in any hospital data
base, so the hospital hires an industrial engineer to calculate this cost for the next 100
patients in each of the two units. If the hospital can show that there is no significant
difference in the average direct nursing cost between units, they will be allowed to use
one estimate for each unit. Otherwise, they will be required to use a different estimate
for each unit. (a) determine if there is a significant difference in the average direct
nursing cost between the two units, (b) estimate the average direct nursing cost with a
point estimate and 95% confidence interval [if you find a significant difference in part a,
you will need an estimate for each of the two units, otherwise use all the data to
estimate the average direct nursing cost]

2. Paired Difference in Means: A HMO launches an intensive campaign to increase the
productivity of the health care professionals in the system with an intensive training
program. Following this one month training session, the productivity of 40 randomly
selected health care professionals was measured. Their productivity, before training,
for these same 40 professionals was also determined. (a) did the training significantly
increase their average productivity, (b) if so, by how much. By the way, this intensive
training program will end up costing around \$1000 per professional and there are
50,000 professionals in the HMO so it is important to make sure there actually is an
increase in productivity and the magnitude of this increase is large enough to recover
the cost of the training.
CHAPTER 14

CHAPTER 15

```
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
 views: 1 posted: 2/24/2012 language: pages: 7