Solutions Manual Fundamentals of Biostatistics 8th Edition Bernard Rosner

Solutions Manual Fundamentals of
Biostatistics 8th Edition Bernard Rosner
Section 1: Descriptive Statistics and Probability Distributions
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1. The median is preferred over the mean as a measure of central tendency when:
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A) The data are normally distributed
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B) The data contain outliers or are skewed
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C) The data are measured on a nominal scale
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D) The sample size is very large
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Answer: B – hg hg




The median is robust to outliers and skewed data, making it a better measure of central tende
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ncy when these conditions exist .
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2. Which of the following statements about the standard normal distribution is FALSE?
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A) Its mean is 0
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B) Its variance is 1
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C) It is symmetric about 0
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D) Its support is from 0 to 1
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Answer: D – The standard normal (Z) distribution has infinite support from -
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∞ to +∞, not from 0 to 1 .
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3. The Z-score is calculated as:
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A) (observed value - mean) / variance
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B) (observed value - mean) / standard deviation
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C) (observed value - standard deviation) / mean
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D) (mean - observed value) / standard error
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Answer: B – Z = (observed value - hg hg hg hg hg hg hg




mean) / standard deviation. It measures how many standard deviations an observation is from
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the mean . hg hg




4. For the binomial distribution, which condition makes the Poisson approximation most
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appropriate?
g

,A) Large n and small p
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B) Small n and large p
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C) Large n and large p
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D) n and p are equal
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Answer: A – hg hg




The Poisson approximation to the binomial is appropriate when n is large and p is small (the r
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are events condition) .
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5. Suppose the expected number of deaths due to bladder cancer over 20 years is 1.8, an
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d 6 deaths are reported. Using the Poisson distribution, the probability of exactly 6 deat
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hs is: hg




A) 0.010
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B) 0.025
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C) 0.050
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D) 0.100 hg




Answer: A – Using the Poisson distribution with λ = 1.8, P(X = 6) is approximately 0.010 .
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Section 2: Confidence Intervals and Hypothesis Testing
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6. A 99% confidence interval will be ______ than a 95% confidence interval for the same d
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ata.

A) Narrower
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B) Wider
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C) The same width
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D) Impossible to determine
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Answer: B – hg hg




Higher confidence requires a larger multiplier (z or t), which widens the interval, providing gre
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ater certainty but less precision .
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7. If a test has a p-value of 0.06 at α = 0.05, the correct decision is:
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A) Reject H₀ and conclude significance
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B) Fail to reject H₀ and conclude no statistically significant effect
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C) Accept H₀ as true
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D) Recompute with a larger sample
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,Answer: B – hg hg




Since p > 0.05, we fail to reject the null hypothesis. However, we do not "accept" H₀ as true; w
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e simply lack evidence to reject it .
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8. A Type I error is defined as:
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A) Failing to reject a false null hypothesis
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B) Rejecting a true null hypothesis
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C) Correctly rejecting a false null hypothesis
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D) Correctly not rejecting a true null hypothesis
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Answer: B – Type I error = false positive, with probability α (the significance level) .
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9. A researcher plans to compare the means of two independent groups with sample size
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s of 30 each and normally distributed data. Which test is most appropriate?
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A) Paired t-test
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B) Independent samples t-test
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C) Mann-Whitney U test
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D) One-way ANOVA
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Answer: B – hg hg




For comparing means of two independent groups with normally distributed data, the indepen
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dent samples t-test is appropriate .
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10. The standard error (SE) differs from the standard deviation (SD) in that:
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A) SE is always larger than SD
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B) SE measures variability of sample means, while SD measures variability of individual observat
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ions
C) SE is used for descriptive statistics only
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D) SE does not depend on sample size
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Answer: B – hg hg




SE is the standard deviation of the sampling distribution of the mean, while SD measures varia
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bility of individual observations. SE = SD/√n .
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Section 3: ANOVA and Regression hg hg hg hg

, 11. In a multiple regression model Y = β₀ + β₁X₁ + β₂X₂ + ε, the coefficient β₁ represents
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:

A) The change in Y for a 1-unit change in X₁, holding X₂ constant
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B) The change in Y for a 1-unit change in X₁, ignoring X₂
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C) The intercept when X₁ = 0
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D) The change in Y for a 1-unit change in X₂
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Answer: A – hg hg




In multiple regression, β₁ is the partial regression coefficient representing the change in Y for a
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1-unit change in X₁ while holding all other variables constant .
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12. The F-statistic in a one-way ANOVA is calculated as:
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A) MS(between) / MS(within)
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B) MS(within) / MS(between)
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C) SS(between) / SS(within)
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D) SS(total) / SS(between)
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Answer: A – hg hg




F = mean square between groups divided by mean square within (error). A large F suggests gr
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oup means differ significantly .
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13. The degrees of freedom for the chi-
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square test of independence in a 3×4 contingency table are:
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A) 12hg




B) 11hg




C) 6 hg




D) 2 hg




Answer: C – df = (r-1)(c-1) = (3-1)(4-1) = 2 × 3 = 6 .
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14. In a scatterplot, if the points fall exactly on a straight line with a positive slope, the c
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orrelation coefficient r equals: hg hg hg




A) 0 hg




B) -1hg




C) +1hg




D) 0.5hg




Answer: C – Perfect positive linear correlation yields r = +1.0 .
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