Microsoft word - aps 12-13 exam c (final)

MARK THE BEST ANSWER TO EACH OF THE FIRST 15 QUESTIONS ON THE SCAN PAGE Which of the following is the best reason why we use the standard normal distribution (z) when conducting inference for proportions rather than switching to the t p is an unbiased estimator of p . A drug company tested the effectiveness of a new anti-anxiety medication. Of 200 people who took the new medication, 64 reported feelings of anxiety. Of the 200 people who took a placebo, 92 reported feelings of anxiety. Which of the following is the margin of error when constructing a 95% confidence interval for the difference in proportion of people who experience anxiety? Which of the following best describes the reason why there are n −1 degrees of freedom in a one sample t test for the population mean? It increases the amount of variability in A study was conducted concerning the earnings of people whose parents had been incarcerated. A large group of adults with at least one living, incarcerated parent were found, and a random sample of 50 of these adults had their current yearly earnings measured. The current yearly earnings of the parents of these people were also measured. Which of the following would be the most appropriate test in order to determine if there is a difference in the mean earnings of the children and their parents?
An experiment tested two different treatments for cocaine addiction— Desipramine and
lithium—and measured whether or not each patient suffered a relapse during treatment.
Patients involved in the experiment were randomly assigned to one of three groups. The
data collected from the experiment are shown below.
Treatment
Desipramine
Use this information for the next two questions.

Which of the following is the appropriate degrees of freedom for conducting a Chi Which of the following is the correct Chi Square test that should be conducted with Among 10 randomly selected men who took a calcium supplement, the mean reduction in systolic blood pressure after 12 weeks was 5mmHg (with standard deviation 8.74 mmHg). Among the 11 men randomly assigned to the control group, the mean reduction was -0.273 mmHg (with standard deviation 5.9 mmHg). What is the value of the test statistic in a test of H : µ = µ versus H : µ ≠ µ ? A study found that people had a decrease in their range of motion as their age increased—in particular, the researchers determined that 99% of the variation in range of motion could be explained by a linear relationship with age. Which of the following is the correlation coefficient for their data? Data were collected concerning the number of hours spent studying for the SAT and the score on the math section of the SAT. The data showed that students studied between 1 and 22 hours, and their scores ranged from 390 to 790. The following model was fitted to the data: A student wants to predict the hours spent studying for a person who scored 360 on the math section of the SAT. Which of the following best describes why this model cannot be used for that purpose? An analysis of speed (kilometers per hour) and fuel consumption (liters per hundred kilometers) was performed, and a least squares model was obtained. At a particular speed, the observed fuel consumption was 21 liters per hundred kilometers, and the residual fuel consumption was 10.089 liters per hundred kilometers. What fuel consumption did the model predict? Estimate Std. Error t value Pr(>|t|) At a sample of professional baseball stadiums, the price of a regular soda and a hot dog were recorded. A linear model was fitted to the data—a portion of the computer output for that process is given above. Which of the following is the best interpretation of the slope of this model? For a $1 increase in the cost of a soda, For a $1 increase in the cost of a soda, A non-linear data set was analyzed, and the following model was found to be a good What response does this model predict when x = 5 ? A basketball player has a 60% chance of making a free throw shot. Which of the following methods would correctly simulate this player attempting five free throw shots? Let 0 – 5 represent making a shot, and Let 0 – 5 represent making a shot, and The manager of a high rise apartment complex wants to survey the residents about a proposed renovation of the building. He randomly selects five of the twenty floors in the building, then surveys every resident on those floors. Which of these best describes the sampling technique that is being employed? Which of the following is the best reason why blocking is used in experiments? ANSWER ALL REMAINING QUESTIONS IN THE SPACES PROVIDED. 16.
The New York State Psychiatric Institute sponsored a study of the use of the drug risperidone to
treat patients suffering from Alzheimer’s Disease. Of the 32 patients that received the drug, 17
experienced relief from their symptoms during the study. Of the 40 patients that received a
placebo, 16 experienced relief from their symptoms.
Do the data suggest that risperidone is more effective than a placebo in treating the symptoms of
Alzheimer’s? Support your conclusion with appropriate statistical evidence.
17.
Can you predict IQ from the size of your brain? A group of 40 volunteers were recruited, and
each was subjected to 18 MRI scans of their brains. The size of each subject’s brain was
measured by counting the total number of pixels that the brain covered in the MRI scans. Each
subject was also given the Wechsler IQ test. The researchers then fit a linear model to the data. A
summary of the results are shown below:
Estimate Std. Error t value Pr(>|t|) Residual standard error: 22.78 on 38 degrees of freedom Multiple R-squared: 0.1279, Adjusted R-squared: 0.105 F-statistic: 5.573 on 1 and 38 DF, p-value: 0.02347 (a) Write the equation of the least squares regression line for these data. (b) Interpret the slope of the least squares regression line in the context of this study. (c) Interpret the y-intercept of the least squares regression line in the context of this study. (d) The value of the test statistic for a t-test for slope has been omitted from the output above. Calculate the value of the statistic.
18.
An study was conducted to determine if gastric freezing was effective in reducing pain due to
stomach ulcers. A large number of patients with stomach ulcers were recruited for the study, and
each was subjected to the gastric freezing technique. A significant majority of the patients
experienced relief from their pain after the study was concluded.
(a) This study did not include a control group. Explain why the patients’ pain relief cannot be
attributed to the gastric freezing procedure.
(b) A follow up study included a control group, where patients were subjected to a procedure that
appeared identical to the gastric freezing technique (but in fact did nothing).
Describe a procedure that could be used to assign patients to the treatment and control groups in
order to make this a completely randomized experiment.
(c) Would it be possible to make this new experiment double blind? Justify your answer.
(d) The study measured the proportion of patients in each group that reported pain relief after the
procedure. What method of inference would be used to determine if there was a significant
difference between the two groups?

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