Practice Questions for Exam 1 Material
1. T
F
Increasing the confidence level for a confidence interval will decrease the margin of error.
2. T
F
A study was conducted to determine whether a new treatment for endometriosis is better than the
current treatment. The study was determined to be statistically significant, thus the researcher
obtained a large p-value.
3. T
F
A study was conducted to determine whether a new medication caused severe side effects in
patients. A random sample of 200 patients was taken and whether or not the patient had side effects
was recorded. This is an example of a numeric variable.
4. T
F
A confidence interval provides a range of likely/plausible/possible values for a statistic.
Use the following scenario and dotplot to answer questions 7 – 9.
Researchers often use alternative forced choice procedures to assist in the evaluation of subjects they suspect are
exaggerating their health issues. In one such case, a patient claimed to suffer from memory loss so severe that they
couldn’t remember what had happened only seconds earlier. To investigate this claim, researchers presented the
patient with one of five objects: a black pen, a green highlighter, a yellow pencil, a red crayon, or an orange marker.
After presentation of the object, the patient was asked to recall which of the five objects had been displayed (note:
the patient could not answer “I don’t know” – they were forced to answer with one of the five options). This process
was repeated a total of 30 times and the patient correctly identified the object 3 times. Consider the following
outcomes from a simulation study with 100 trials.
Research Question – Is there evidence that the patient is really exaggerating memory loss?
5. Which of the following is most correct about the dotplot given above?
a. The dotplot was constructed under the assumption that the patient is exaggerating memory loss.
b. The dotplot was constructed under the assumption that the patient is not exaggerating memory loss.
c. The dotplot was not constructed correctly because there aren’t enough dots at 3.
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6. Which of the following is most correct regarding the estimated p-value one might compute from the dotplot
given above?
a. The estimated p-value would be about 10% because 3/30 is the percent of times the patient correctly
identified the object.
b. The estimated p-value would be about 6% because 6/100 dots are at 3.
c. The estimated p-value would be about 13% because 13/100 dots are at 3 or smaller.
d. The estimated p-value would be about 87% because 87/100 dots are at 3 or larger.
7. Which of the following statements is most correct about the patient suffering from memory loss?
a. The dotplot and p-value provide no evidence for the research question. That is, it can be concluded
that the patient is exaggerating memory loss.
b. The dotplot and p-value provide no evidence for the research question. That is, it cannot be
concluded that the patient is exaggerating memory loss.
c. The dotplot and p-value provide marginal evidence for the research question. That is, it can be
concluded that the patient is exaggerating memory loss.
d. The dotplot and p-value provide marginal evidence for the research question. That is, it cannot be
concluded that the patient is exaggerating memory loss.
8. In a 2003 study on dreaming, an investigator attempted to replicate an experiment done by Middleton in
1941 (Schwitzgebel, Perceptual and Motor Skills, 2003). In the study from 2003, 92 of the 113 people said
they dream in color.
a. Suppose it was of interest to construct a 90% confidence interval to estimate the true proportion of
people who dream in color. Circle the corresponding JMP output below.
b. Using the JMP output chosen in part a, give the 90% confidence interval for the true proportion of
people who dream in color.
0.75 ≤ p ≤ 0.87
c. Interpret the 90% confidence interval identified in part b.
90% confident the true proportion of people who dream in color is between 0.75 and 0.87
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9. Previous research has found that 85% of people survive after suffering from a stroke. A drug company is
interested in marketing a new drug which they claim would increase the survival rate if taken immediately
after suffering from a stroke. In the clinical trial the new drug was given to 300 randomly selected individuals
who had just suffered from a stroke and 264 of them survived.
Research Question – Do these data provide evidence that the new drug increases the
survival rate if taken immediately after suffering from a stroke?
a. Define the population of interest.
All people who suffer from strokes
b. Define the sample for the study.
300 people who suffer from strokes
c. Define the variable of interest for this study.
Survival Status – Survived, Died
d. Suppose you wanted to conduct a simulation study to answer the research question of interest.
Using the empty spinner given below, create the spinner which would be used to simulate this
scenario.
300
0.85
Survive
Die
0.15
e. Describe in context how this scenario could be modeled instead using the binomial distribution.
1.
2.
3.
4.
f.
n = 300 stroke sufferers
Survive, Die
P(Survive) = 0.85 for each stroke sufferer
Stroke sufferers are independent of one another
Assuming 85% of people survive after suffering from a stroke, how many of the 300 people would
you expect to survive?
300(0.85) = 255 survived
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g. Circle the JMP output below which correctly models this situation.
Binomial with n = 300 and p = 0.88
Binomial with n = 300 and p = 0.85
h. Recall 264 of the 300 individuals lived after suffering from a stroke. Using the JPM output chosen in
part g above, find the probability of observing results at least as extreme as observed.
P(X ≥ 264) = 0.0817
i.
Based on the probability found in part h, does this study provide evidence the new drug increases the
survival rate if taken immediately after suffering from a stroke? Explain.
No evidence (0.0817 > 0.05) that the new drug increases the survival rate if taken
immediately after suffering from a stroke.
10. Melanoma is a rare form of skin cancer that accounts for the great majority of skin cancer families. UV
exposure is a major risk factor for melanoma. Some body parts are regularly more exposed to the sun than
others. A random sample of 310 women diagnosed with melanoma was taken and the location of the
melanoma on their body was recorded. The data given below summarize the locations of the melanoma
found on the 310 women sampled.
Location
Count
Head/Neck
45
Trunk
80
Upper Limbs
34
Lower Limbs
151
Total
310
Research Question – Do these data provide evidence that each of the areas of the body is not equally
likely to have melanoma?
a. Set up the null and alternative hypotheses that would be used to test the research question.
H0: pHead/Neck = 0.25
pTrunk = 0.25
pupper limbs = 0.25
plower limbs = 0.25
Ha: Two or more differ, i.e. each of the areas of the body are not equally likely
to have melanoma
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b. Calculate the expected counts that would be used in the computation of the test statistic.
Head/Neck  310(0.25) = 77.5
Trunk  310(0.25) = 77.5
Upper Limbs  310(0.25) = 77.5
Lower Limbs  310(0.25) = 77.5
All expected counts are ≥ 5√
c. Circle the JMP output below that would be used to carry out the analysis.
Test Statistic = 107.8323
p-value = 0.0001
d. Using the p-value chosen in part c, is there evidence the observed data are consistent with the
hypothesized values.
Evidence (0.0001 < 0.05) that each of the areas of the body are not equally likely to have
melanoma
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