BIOSTAT FINAL EXAM QUESTIONS & ANSWERS 2024/2025
Which of the following statement(s) about ANOVA is(are) true?
A. The ANOVA test assumes that the data are normally distributed
B. The ANOVA test assumes that the sampled populations have identical variances
C. The ANOVA test is used to comp...
Which of the following statement(s) about ANOVA is(are) true?
A. The ANOVA test assumes that the data are normally distributed
B. The ANOVA test assumes that the sampled populations have identical variances
C. The ANOVA test is used to compare variances
D. The ANOVA test is used to compare means - ANSWERSA, B and D
Which of the following statements best illustrates the Decision Rule for ANOVA? - ANSWERSAt a given
alpha we reject the null hypothesis if calculated test statistic (Fcalc) is greater than F(1-alpha)dfn, dfd
Suppose that the coefficient of determination is 0.90 for a linear regression model between Heart Rate
(X) and Pulse Pressure (Y). Interpret this value - ANSWERS90% of variation in pulse pressure is explained
by heart rate
Which of the following statements about correlation coefficient and coefficient of determination are
correct? - ANSWERSA. -1 ≤ r ≤ 1
B. 0 ≤ r2 ≤ 1
Failing to reject the null hypothesis of zero slope (Ho: beta1 = 0) in the simple linear regression model
indicates that there is - ANSWERSNo statistically significant linear relationship between the independent
and dependent variables.
True or False: One-tailed tests of significance always produce smaller p-values than a two-tailed test
applied to the same data and using the same test statistic. - ANSWERSTrue
Circulating levels of estrone were measured in a sample of 30 postmenopausal women following
estrogen treatment. The sample mean and standard deviation were 73 and 16, respectively. At the 0.05
,significance level, can one conclude on the basis of these data that the population mean is different than
70?
Assume the computed test statistic is 2.0 and your critical value was 2.5, state your statistical decision.
(Note: Do not recalculate the actual values, use the assumed values.) - ANSWERSFail to reject the null
Forty people with high cholesterol take part in a study of a new drug for reducing blood cholesterol
levels. Blood cholesterol levels among these individuals are measured before the medication is started
and 12 weeks later. It is assumed that cholesterol measures are normally distributed. The researcher
wants to know if this data provides sufficient evidence to suggest that the new drug reduces cholesterol
levels.
What procedure should you use? - ANSWERSPaired t-test
An exercise physiologist wants to determine if several short bouts of exercise provide the same
cardiovascular benefit as one long bout of exercise. She obtains 90 volunteers and assigns 45 to the short
bout group and 45 to the long bout group. Cardiovascular fitness is measured by maximum oxygen
consumption while exercising and maximum oxygen consumption is assumed to be normally distributed.
The researcher wants to know if this data provides sufficient evidence to conclude that the
cardiovascular benefit is different between the two groups. The 95% confidence interval for the ratio of
two population variances includes 1.
What procedure should be used to decide if the mean maximum oxygen consumption is different
between the two groups? - ANSWERST-test: two independent means assuming equal variances
For the following problem, what is the appropriate reliability coefficient (t or z value)
In a study of childhood abuse in psychiatric patients, it was found that 166 in a sample of 515 patients
reported histories of physical and/or sexual abuse. Construct a 99% confidence interval for the
population proportion of those who reported histories of abuse. - ANSWERS2.58
For the following problem, what is the appropriate reliability coefficient (t or z value)
In a study of childhood abuse in psychiatric patients, it was found that 166 in a sample of 947 patients
reported histories of physical and/or sexual abuse. Construct a 90% confidence interval for the
population proportion. - ANSWERS1.65
For the following problem, what is the appropriate reliability coefficient (t or z value)
, In a study of childhood abuse in psychiatric patients, it was found that 166 in a sample of 588 patients
reported histories of physical and/or sexual abuse. Construct a 90% confidence interval for the
population proportion of those who reported histories of abuse. - ANSWERS1.65
A study was performed to examine free fatty acid concentration in 18 lean subjects and 11 obese
subjects. The lean subjects had a mean level of 299mcEq/L, with a standard deviation of 22, while the
obese subjects had a mean of 744mcEq/L with a standard deviation of 14. Fatty acid concentration is
known to be approximately normally distributed.
If we're interested in a confidence interval around the difference between these two population means,
what is the number of degrees of freedom to find the reliability coefficient?
Can we assume the two population variances are equal based on the Equal Variance Rule of Thumb? -
ANSWERSdf=27
variances are not equal
Equal Variance Rule of Thumb: - ANSWERSif the larger sample variance is more than twice as large as the
smaller sample variance then the population variances are unequal
What is the distribution we use for calculating a confidence interval around a single variance of normally
distributed population?
z distribution
t distribution
chi-square distribution
F distribution - ANSWERSchi-square distribution
A sample of 18 twelve-year old girls had a mean weight of 80.0 pounds and a standard deviation of 15
pounds (estimated from the data). What is the appropriate reliability coefficient (t or z value), if we're
interested in a 95% confidence interval around the population mean weight? Assume a normal
distribution for the weight. - ANSWERS2.1098
Systolic blood pressure of 12 patients has a mean of 120 mm/Hg. If the population variance of the
systolic blood pressure is 25 and the SBP is approximately normally distributed in the population, find
the reliability coefficient for a 95% confidence interval for a single population mean. - ANSWERS1.96
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