Question 1:
By definition, a ‘fair’ coin has a probability of heads of p = 1/2. The standard deviation (SD) associated with a single toss is sqrt( p*(1-p) ). if a fair coin is tossed n=16 times, what is the standard error (SE) for the proportion of times a heads occurs?
1/2
1/16
1/8
None of the above
1 points
QUESTION 2
If a continuous variable (e.g., BMI) is normally distributed, what percent of data is expected to occur between plus or minus 1 standard deviation from the mean?
99.7%
2.5%
95%
68%
1 points
QUESTION 3
Given that a population of scores is normally distributed with a mean of 100 and a standard deviation of 8, determine the Z score of X = 112.
+1.5
-1.5
99.5
12
1 points
QUESTION 4
The standard error of the mean is best defined as the
sum of squares of a sample divided by the appropriate degrees of freedom.
error that occurs when a mean falls in the critical region of a hypothesis test.
z score of a mean.
standard deviation of the sampling distribution of Xbar (sample mean).
1 points
QUESTION 5
When conducting a hypothesis test, Ha symbolizes the
research hypothesis
null hypothesis
power
sample mean
1 points
QUESTION 6
Use the information provided here to answer the following questions. H0 : µ 60, n = 36, Xbar = 58. Which of the following best characterizes this test?
The information provided characterizes a one sample, one-tailed (i.e., one-sided) t test.
The information provided characterizes a one sample, one-tailed proportion test.
The information provided characterizes a 95% confidence interval for the mean.
The information provided characterizes a one sample, two-tailed t test.
1 points
QUESTION 7
Use the information provided here to answer the following questions. H0 : µ 60, n = 36, Xbar = 58. Assuming the conventional type 1 error (alpha), which of the following would be the correct decision to make based on the information?
p = 0.274, p > 0.05 and H0 is not rejected.
p = 0.274, p < 0.05 and H0 is rejected.
p = 0.274, p 0.05 and Ha is not rejected.
1 points
QUESTION 8
As the sample size (n) increases, the standard error of the sampling distribution for the summary statistic (e.g., mean) of interest should
Decrease.
Increase.
Stay the same.
Not enough information.
1 points
QUESTION 9
Researchers A and B separately took samples from the same population of epilepsy patients, each with the same sample size. Researcher A calculated a mean seizure rate of 4.1 per week, with 95% confidence interval of (0.1, 8.1). Researcher B calculated a mean seizure rate of 4.2 per week, with 95% confidence interval of (0.8, 7.6). These results indicate that Researcher A’s study assessed seizure rate with a greater precision of estimation
True
False
1 points
QUESTION 10
Confidence intervals are used to estimate
standard errors.
sampling distributions.
sample statistics.
population parameters.
1 points
QUESTION 11
Which of the following will increase the width of a confidence interval?
Increasing sample size.
Decreasing the level of confidence (e.g. going from 95 to 90% confidence).
Finding that the population parameter being estimated is outside the confidence interval.
Increasing the level of confidence (e.g. going from 90 to 95% confidence).
1 points
QUESTION 12
When calculating statistical power, increasing the sample size (n) will
increase power.
decrease power.
increase type 1 error.
Make it more likely that the results of the study will be criticized.
1 points
QUESTION 13
A summary of a feature of a population is referred to as
a sample.
a statistic.
a parameter.
an inference.
1 points
QUESTION 14
By one convention, Greek letters (µ, α , β) are used to characterize
erroneous data.
sample statistics.
inferences.
population parameters.
1 points
QUESTION 15
The discipline of statistics may be conceptually divided into which of the following major categories?
Descriptive and inferential statistics.
Finite and infinite statistics.
Exact and approximate statistics.
Theoretical and research statistics.
1 points
QUESTION 16
In the hemodialysis example in the class slides, a p-value of 0.31 was calculated for the test of H0: p = 0.86, where p = probability of a successful hemodialysis session. Since the p-value is large, which of the following is true?
The sample proportion must be less than 0.86.
It is fairly clear that the null hypothesis is true.
The population probability is less than 0.86.
If we set the probability of a type 1 error (alpha) at a reasonable level, we cannot reject the null hypothesis.
1 points
QUESTION 17
The statistical analyst obtained BMI measurements for 100 subjects and calculated the standard error of the mean (SEM) as 1.00. What is the sample standard deviation (SD) for BMI in this data set?
20.0
5.0
10
15.5
1 points
QUESTION 18
The statistical analyst in the question above defines obesity as having a BMI > 30, and finds that 25 of the 100 subjects have BMI > 30. What is the estimated standard error (SE) associated with the sample proportion of obese subjects?
3.1515
0.0433
0.7560
2.5000
1 points
QUESTION 19
The data shown below describe children in four countries in terms of adequate dental care.
Adequate Dental Care
Inadequate Dental Care
UK
2520
180
US
4560
240
France
1100
300
Mexico
2820
280
What is the estimated probability that a child from France has inadequate dental care?
300/3100
180/12000
300/1400
1100/11000
1 points
QUESTION 20
The data shown below describe children in four countries in terms of adequate dental care.
Adequate Dental Care
Inadequate Dental Care
UK
2520
180
US
4560
240
France
1100
300
Mexico
2820
280
What is the estimated probability that a child from the US has adequate dental care?
240/11000
4560/11000
4560/4800
240/12000
1 points
QUESTION 21
Given that a population is normally distributed with a mean of 100 and a standard deviation of 8, determine the Z score of X = 88
+1.5
12
-1.5
99.5
1 points
QUESTION 22
True or False? Sampling distributions are created assuming a fixed sample size, n.
True
False
1 points
QUESTION 23
True or False? The probability of a Z score being less than 0 is 84%.
True
False
1 points
QUESTION 24
True or false? Even with small sample sizes (e.g. 15 people), the sampling distribution will always be exactly normally distributed
True
False
1 points
QUESTION 25
The central limit theorem (CLT) guarantees that any sample proportion is approximately normally distributed.
True
False
1 points
QUESTION 26
True or False? If there are outliers, then the mean will always be greater than the median.
True
False
1 points
QUESTION 27
A medical research team studied the number of head and neck injuries sustained by hockey players. Of the 319 players who wore a full-face shield, 195 sustained an injury. Of the 323 players who wore a half-face shield, 204 sustained an injury. Which statistical test would be most appropriate to compare the protective benefits of full vs half-face shields?
A one sample Z test for sample proportions
A two sample Z test for sample proportions
A two sample t test for sample means
A one sample t test for sample means
1 points
QUESTION 28
An education organization claims that the mean SAT scores for male athletes and male non-athletes at a college are different. A random sample of 26 male athletes at the college has a mean SAT score of 1783 and a standard deviation of 218. A random sample of 18 male non-athletes at the college has a mean SAT score of 2064 and a standard deviation of 186. Which test would best be used to compare SAT scores between these groups?
A one sample Z test for sample proportions
A two sample Z test for sample proportions
A two sample t test for sample means
A one sample t test for sample means
1 points
QUESTION 29
The distribution of systolic blood pressure (SBP) tends to be symmetric and bell-shaped for adults between the ages of 45-55. An investigator wishes to calculate a 95% confidence interval (CI) for mean SBP based on a sample of n=20 adults in this age range. Which of the following is the most appropriate formula for the upper limit of the 95% CI?
sample mean + 2.09*SEM
sample mean + 2.18*SEM
sample mean – 1.99*SEM
sample mean + 1.96*SEM
1 points
QUESTION 30
The mean change in muscle thickness observed after a 4-week training regimen was 4 mm, and the 95% confidence interval (CI) for mean change was (-0.5, 8.5). Which is the best scientific conclusion for the effectiveness of this regimen?
An increase in 4 mm is impressive, so the regimen has been proven effective.
Although a mean increase was observed, it is not statistically significant because the 95% CI includes zero change.
The lower limit of the CI is less than zero, which means a new person undergoing this training can be expected to lose muscle thickness.
The upper limit of the CI is greater than 8, which means that an increase of 8 mm is our best prediction for a new person undergoing this training.
