Biostat Exam 1 Questions & Answers 2024/2025
In an experimental study where there are three levels of a treatment (usual care, education, education + social support) and you want to determine if the means across the 3 treatments are statistically different, what statistical procedure is best? ...
In an experimental study where there are three levels of a treatment (usual care, education, education +
social support) and you want to determine if the means across the 3 treatments are statistically
different, what statistical procedure is best? - ANSWERS1-way ANOVA
A sample of 80 children with chronic ear infections were treated with 1 of 4 drugs. After 3 months of
treatment, parent satisfaction was measured across the 4 groups. The calculated ANOVA F statistic
=2.424. If the critical F value is 2.725, what would your decision be about the null hypothesis? -
ANSWERSThe calculates F value is less than the critical F value, therefore the null hypothesis must be
accepted.
If you intended to do a 1-way ANOVA but could only collect data on 7 patients in each of the three
treatment arms, what non-parametric alternative could you use? - ANSWERSKruskal-Wallis
The effect size estimate in an ANOVA is known a the - ANSWERSEta-squared
A nurse is studying the job satisfaction among different levels of nurses. Her research is to see if there is
a statistically significant difference in mean job satisfaction scores (continuous variable with normal
distribution) for registered nurses, licensed practice nurses and unlicensed assistive providers -
ANSWERSANOVA
Three groups of students study a passage of text for 30 minutes. Those in group 1 study with background
noise at a constant volume. Those in group 2 study with noise that changes volume periodically. Those in
group 3 study with no sound at all. After studying, all students take 10 point multiple choice tests
(interval but non-normally distributed) over the material. What test do you use to determine if students
will learn most effectively with a constant background sound, as opposed to an unpredictable sound or
no sound at all. - ANSWERSKruskal-Wallis
A medical researcher identifies 3 well-known pain killer drugs (drug A, drug B, drug C) and recruits a
group of 30 individuals with a similar level of back pain and randomly assigns them to one of the three
treatment groups for a 4 week period. At the end of the 4 weeks, the researcher asks the participants to
rate their back pain. The researcher wishes to compare the levels of pain (ordinal) experienced by the
,different groups at the end of the drug treatment period. What statistical approach do you recommend?
- ANSWERSKruskal-Wallis
All of the following are assumptions for ANOVA except - ANSWERSNormal distribution of the
independent variable
In its basic form, the ANOVA contrasts - ANSWERSBetween group variances to within group variances
Calculate the effect size for the following output. The effect size is - ANSWERS(Sum of squares between
groups)/(sum of squares total)
A nominal level of measurement is used when the values of a variable have which of the following
properties?
a. They can be placed in meaningful order, have meaningful intervals between each other, but there is no
true zero
b. They can be placed in meaningful order, have meaningful intervals between each other, and have a
true zero
c. They can be placed in meaningful order, but there is no information about the size of the interval
between each value
d. They represent independent categories - ANSWERSThey represent independent categories
Why are we interested in determining the level of measurement?
a. The level of the dependent variable determines what stat test we can run
b. The level of the independent variable determines what stat test we can run
c. We need to know what the value labels stand for
d. We need to know which variable is larger than the others - ANSWERSA. The level of the dependednt
variable determines which stat test we can run
Which of the following is an example of a dichotomous variable?
a. BMI
b. belief in the tooth fairy
c. military ranking
,d. marital status - ANSWERSBelief in the tooth fairy
What kind of statistics can we use to describe an ordinal variable?
a. Means
b. Standard deviations
c. Proportions
d. Inferential statistics - ANSWERSC. Proportions
Which of the following in NOT a demographic variable?
a. number of children
b. gender
c. weight
d. ethnicity - ANSWERSC. Weight
Which of the following is true about missing values
a. they are always assigned the value of '9'
b. they can lead to misleading results because of bias
c. you can ignore if more than 20% of your sample provided responses
d. they make analysis easier because less data to deal with - ANSWERSb. they can lead to misleading
results because of bias
You are interested in evaluating how compliance with the DASH diet affects the stage of high blood
pressure. You follow criteria to assess blood pressure as normal, prehypertensive, stage I hypertension,
stage II hypertension, hypertensive crisis. Compliance will be a count of how many days the diet was
followed in the past week.
a. What is the independent variable?
b. What is the level of measurement of the independent variable? - ANSWERSa. IV = compliance
b. Interval/ratio
, You are interested in evaluating how compliance with the DASH diet affects the stage of high blood
pressure. You follow criteria to assess blood pressure as normal, prehypertensive, stage I hypertension,
stage II hypertension, hypertensive crisis. Compliance will be a count of how many days the diet was
followed in the past week.
a. What is the dependent variable?
b. What is the level of measurement of the dependent variable? - ANSWERSa. DV = blood pressure
b. ordinal (categories with ordering)
When working with a datafile one can refer to a codebook to understand what kinds of things? -
ANSWERSwhat 'question/piece of information' the variable is referring to. How responses were coded
and what the codes mean
What are three good practices to think about when it comes to missing values? - ANSWERSdetermine
how many ( if <5% might be OK), note how they are coded as might need to be careful doing analyses,
inform the reader when reporting findings
What level of measurement would be used if a participant was asked to report their level of pain on a
scale that ranged from "Worst pain I have ever had" to "No pain"?
a. Ratio
b. Interval
c. Nominal
d. Ordinal - ANSWERSD. ordinal
Which of the following is a Ratio level of measurement?
a. A patient's temperature in the morning
b. A patient's medical record number
c. A patient's weight in the morning
d. A patient's room number - ANSWERSC. a patients weight in the morning
An experiment was conducted in the middle of the Summer to test the efficacy of various sun blocks in
protecting participants' skin from the harmful effects of the sun. Two types of sunblock were used, and
researchers monitored the participants skin for signs of sunburn, controlling for amount of sun exposure.
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