CPH Study Guide

The lengths of stay for six patients were 0, 0, 1, 2, 2, and 16 days. Which is (are) the best measure(s) to summarize these data?

[removed]	1.	Mean
[removed]	2.	Median
[removed]	3.	Median and standard deviation
[removed]	4.	Mean and standard deviation
[removed]	5.	Median and range

An epidemiologist attempts to predict the weight of an elderly person from demispan. She randomly chooses 70 elderly subjects in a particular geographic area and records their weight and demispan measurements in the form of (xi, yi) for i = 1,. . . ,70
Given that the value of the Pearson correlation coefficient is zero, what can be deduced?

[removed]	1.	There is no relation between weight and demispan
[removed]	2.	There is an almost perfect relationship between weight and demispan
[removed]	3.	There could be some nonlinear relationship between weight and demispan
[removed]	4.	There is a strong negative relationship between weight and demispan
[removed]	5.	All pairs of values of weight and demispan are practically identical

Which of the following statistical tests is not considered a nonparametric test?

[removed]	1.	Kruskal-Wallis test
[removed]	2.	Wilcoxon rank-sum test
[removed]	3.	Tukey's test
[removed]	4.	Mann-Whitney test

What is the underlying distribution assumption of the data for a two-sample t-test for independent samples with equal variances?

[removed]	1.	Binomial
[removed]	2.	Poisson
[removed]	3.	Chi-square
[removed]	4.	Normal
[removed]	5.	Student t-distribution

The percentages on the y axis of a relative frequency histogram represent:

[removed]	1.	Widths
[removed]	2.	Proportions
[removed]	3.	Frequencies
[removed]	4.	Intervals

A researcher is designing a new questionnaire to examine patient stress levels on a scale of 0 to 5. What type of outcome variable is being collected?

[removed]	1.	Ratio
[removed]	2.	Nominal
[removed]	3.	Interval
[removed]	4.	Ordinal
[removed]	5.	Binary

If the chances for a second event to occur stay the same, regardless of the outcome of a first event, then the two events are:

[removed]	1.	Equally likely
[removed]	2.	Independent
[removed]	3.	Indeterminate
[removed]	4.	Mutually exclusive

In simple linear regression, what is a method of determining the slope and intercept of the best-fitting line?

[removed]	1.	Least squares
[removed]	2.	R-square
[removed]	3.	Minimum error
[removed]	4.	Least error
[removed]	5.	Odds ratio

In a group of individuals, the probability of characteristic C is 0.4, and the probability of characteristic D is 0.2. The probability of their intersection is 0.10. Which of the following statements is correct?

[removed]	1.	Characteristics C and D are independent
[removed]	2.	Characteristics C and D are not independent
[removed]	3.	Characteristics C and D are mutually exclusive
[removed]	4.	Characteristics C and D are independent and mutually exclusive
[removed]	5.	Not enough information is given about the relationship between the two variables to ascertain the answer

If we have a list of numbers, and then add the number "2" to all the values in the list, what happens to the standard deviation?

[removed]	1.	It is increased by 2
[removed]	2.	It is increased by 4
[removed]	3.	It is unchanged
[removed]	4.	Cannot be determined without the actual list of numbers

The sensitivity of a particular screening test for a disease is 95%, and the specificity is 90% Which of the following statements is most correct?

[removed]	1.	Of 100 people sampled from a population with the disease, the test will correctly detect 95 individuals as positive for the disease
[removed]	2.	Of 100 people sampled from a population with the disease, the test will correctly detect 90 individuals
[removed]	3.	If a person tests positive, the probability of having the disease is 0.95
[removed]	4.	If a person has the disease, there is a 5% chance that the test will be negative
[removed]	5.	If a person does not have the disease, there is a 5% chance that the test will be positive

Which is the most correct statement about a scatterplot?

[removed]	1.	It is used to determine whether to perform a linear regression
[removed]	2.	It shows the relationship between any two variables
[removed]	3.	It is used to compare the means of two variables
[removed]	4.	It is a useless plot when the relationship between two variables is nonlinear
[removed]	5.	It is used to investigate the relationship between two continuous variables

The Central Limit Theorem states that:

[removed]	1.	The sample mean is unbiased
[removed]	2.	The distribution of sample means from a large number of samples drawn from the population will be approximately normal
[removed]	3.	The parent population of the sample distribution is normally distributed
[removed]	4.	The sample standard deviation is approximately normal
[removed]	5.	Both statements (1) and (3) can be deduced from the Central Limit Theorem

Assume that a researcher has measured weight in a sample of 100 overweight adults before and after a diet and exercise program conducted at the local health department's weekly Eat Healthy-Be Fit community program. To determine whether the mean weight decreased six weeks after the exercise program compared to the initial baseline measures, the researcher should:

[removed]	1.	Compute the correlation coefficient, r, and determine the association between being overweight and the community program
[removed]	2.	Conduct a t-test for independent samples
[removed]	3.	Conduct a t-test for dependent samples
[removed]	4.	Conduct a chi-square test for association
[removed]	5.	Not estimate the decrease because there was no control group for the program

Now assume that the researcher has measured weight in a sample of 200 overweight adults who have been randomized to receive either the diet and exercise program (cited in the previous question) or no program (i.e., to serve as a control group). All subjects are weighted at baseline and again six weeks later. Choosing from the following analysis options, which is the most appropriate way to determine whether the diet program had an impact on weight loss?

[removed]	1.	Conduct an independent t-test on the six-week follow-up weight measures between the diet and exercise group and the control group
[removed]	2.	Conduct a paired t-test (baseline and six-week weight) in the exercise program group and then again in the control group and compare the two P-values to determine which group had a statistically significant change
[removed]	3.	Conduct a survival analysis and compute the hazard ratio to determine whether the community program is protective against weight gain
[removed]	4.	Conduct an analysis of covariance using the baseline to six-week weight change scores as the dependent variable and the diet and exercise program versus control group as the independent variable
[removed]	5.	Conduct an analysis of covariance using the weight at six weeks as the dependent variable, the diet and exercise program versus control group as the independent variable, and the baseline eight as a covariate

If a population has a standard deviation of σ, then the standard deviation of the mean of 100 randomly selected items from this population is:

[removed]	1.	σ
[removed]	2.	100σ
[removed]	3.	σ/10
[removed]	4.	σ/100
[removed]	5.	0.1

Select the most correct statement concerning relative risk and odds ratios.

[removed]	1.	A relative risk of 10 has the same strength of association as a relative risk of 0.1.
[removed]	2.	If the confidence interval for the relative risk does not contain 0, there is an association.
[removed]	3.	It is possible to calculate a relative risk when data are from a case-control study.
[removed]	4.	At least one variable should be normally distributed to calculate a relative risk.
[removed]	5.	Coefficients from logistic regression analysis yield relative risk.

Assume that a linear regression analysis is performed. Which of the following results would justify trying a different method of analysis for the data?

[removed]	1.	The constant is not significant
[removed]	2.	The slope coefficient = 0.001
[removed]	3.	The r² = 0.99
[removed]	4.	The r² = 0.001.
[removed]	5.	Plotting the residuals against the dependent variable gives a random cloud of points

A type I error is defined as:

[removed]	1.	The probability of rejecting the null hypothesis when the null hypothesis is true
[removed]	2.	The probability of rejecting the alternative hypothesis when the null hypothesis is true
[removed]	3.	The probability of rejecting the null hypothesis when the alternative hypothesis is true
[removed]	4.	The probability of rejecting the alternative hypothesis when the alternative hypothesis is true

An investigator measures a continuous variable on four independent, disjointed groups of people and would like to know whether the means of each group differ. Which statistical test should the investigator use to answer this question?

[removed]	1.	Logistic regression
[removed]	2.	Cox regression
[removed]	3.	Chi-squared test
[removed]	4.	Analysis of variance

An investigator would like to assess the association between two categorical variables, but a cross-tabulation of the variables reveals that some cells contain counts equal to zero. Which statistical test would be most appropriate in this situation?

[removed]	1.	Scheffe's test
[removed]	2.	Fisher's exact test
[removed]	3.	McNemar's test
[removed]	4.	Student t-test

The proportion of people with a disease who are correctly identified by a screening test as having the disease is called:

[removed]	1.	Sensitivity
[removed]	2.	Specificity
[removed]	3.	Positive predictive value
[removed]	4.	Negative predictive value

The probability that an event occurs if some condition is met is called a:

[removed]	1.	Joint probability
[removed]	2.	Simple probability
[removed]	3.	Conditional probability
[removed]	4.	Marginal probability

Which of the following does not describe a measure of the variability of a continuous variable?

[removed]	1.	Standard deviation
[removed]	2.	Interquartile range
[removed]	3.	Confidence interval
[removed]	4.	Kurtosis

The z-score measures the relative position of one observation relative to others in a data set. What components are needed to compute a z-score?

[removed]	1.	Median and range
[removed]	2.	Mean and range
[removed]	3.	Mean and standard deviation
[removed]	4.	Median and standard deviation

In the construction of Box-plots, the upper and lower fences are used to detect which of the following summary?

[removed]	1.	Outliers
[removed]	2.	Maximum Number
[removed]	3.	Minimum Number
[removed]	4.	Quartiles

A 911 emergency operator is flooded with calls during the daily rush hour period. What is the distribution that best describes this data set?

[removed]	1.	Normal
[removed]	2.	Binomial
[removed]	3.	Hypergeometric
[removed]	4.	Poisson

The ability to reject the null hypothesis when the null is in fact false is called?

[removed]	1.	Type I Error
[removed]	2.	Type II Error
[removed]	3.	Power
[removed]	4.	Level of significance

A clinical experiment with four treatment groups was analyzed using an ANOVA and a significant different in the population means is found. Which of the following a natural next step?

[removed]	1.	Tukey's or a similar method of pairwise comparison
[removed]	2.	Multiple t-test comparison
[removed]	3.	Check model assumptions
[removed]	4.	Power analysis

A doctor would like to estimate a patients' weight based on their age and gender. Age and gender are known as?

[removed]	1.	Response variables
[removed]	2.	Dependent variables
[removed]	3.	Outcome variables
[removed]	4.	Independent variables

Suppose the least squares line resulting from a simple linear regression analysis between weight (y in pounds) and height (in inches) is as follows: y = 135 + 4x. The interpretation of this line is:

If the height is increased by 1 inch on average the weight is expected to:

[removed]	1.	Increase by 4 pounds
[removed]	2.	Decrease by 4 pounds
[removed]	3.	Increase by 1 pound
[removed]	4.	Decrease by 1 pound

One can describe the F-distribution as a sampling distribution of the ratio of which of the following:

[removed]	1.	Two normal population means
[removed]	2.	Two sample variances provided that the samples sizes are large
[removed]	3.	Two normal population variances
[removed]	4.	Two sample variances provided that the samples are independently drawn from two normal population with equal variances

The assumption of a t-test for the difference between the means of two independent populations is that the respective:

[removed]	1.	Sample variances are equal
[removed]	2.	Sample sizes are equal
[removed]	3.	Populations are approximately normal
[removed]	4.	Sample variances are equal, sample sizes are equal and populations are approximately normal

Suppose a researcher calculates a confidence interval for a population mean based on a sample size of 9. Which of the following assumptions have been made?

[removed]	1.	The sampling distribution of z is normal
[removed]	2.	The sampled population is approximately normal
[removed]	3.	The population standard deviation is known
[removed]	4.	No assumptions have been made

What does the abbreviation IQR stand for?

[removed]	1.	Independent query re-sampling
[removed]	2.	Interrelation quantity rescaled
[removed]	3.	Interquartile range
[removed]	4.	Integrated quantal relation
[removed]	5.	Inter-quantile relationship

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