1.
Data were collected in 20 cities on the percentage of women in the workforce. Data were collected in 1990 and again in 1994. Gains, or losses, in this percentage were the measurement upon which the studies conclusions were to be based. What kind of design was this?
I. A matched pairs design
II. An observational study
III. An experiment using a block design
Correct Answer
E. I and II only
Explanation
E - the data are paired because there are two measurements on each city so the data are not independent. There is no treatment being applied, so this is an observational study. Matched pairs is one type of block drain, but this is NOT an experiment, so III is false.
2.
A recent study showed that tea drinkers have lower stress levels than coffee drinkers. Tea drinkers are known to have a higher proportion of yoga practitioners than coffee drinkers, and they exercise on average two hours per week more than their coffee-drinking counterparts. What is the term used to describe these additional factors that might have an effect on the stress levels of tea drinkers?
Correct Answer
C. Confounding variables
Explanation
C- The first sentence may lead one to believe that drinking tea leads to lower stress than drinking coffee. However, the additional data shows inherent differences between tea drinkers and coffee drinkers, which could contribute to the lower stress levels of tea drinkers. Thus, these additional variables may confound the relationship between drinking tea and drinking coffee.
3.
In a survey, students were asked to report the number of hours they study each week. What type of data is this?
Correct Answer
B. Continuous
Explanation
The number of hours students study each week is a continuous variable because it can take on any value within a range (e.g., 0.5 hours, 3.2 hours, 7.8 hours), and it can have decimal places, indicating continuity.
4.
You want to investigate the relationship between the amount of rainfall and crop yield in a farming community. What kind of study is this?
Correct Answer
A. Observational Study
Explanation
This is an observational study because you're observing and collecting data on the existing conditions (rainfall and crop yield) without manipulating any variables.
5.
Which of the following measures of central tendency is most appropriate for skewed data?
Correct Answer
B. Median
Explanation
The median is the most appropriate measure for skewed data because it is not affected by extreme values and provides a better representation of the central value in such cases.
6.
In a survey, respondents were asked to rate a new product on a scale from 1 (poor) to 5 (excellent). What type of data is this?
Correct Answer
C. Ordinal
Explanation
The data is ordinal because the categories (poor, fair, good, very good, excellent) have a clear order, but the intervals between them are not consistent or meaningful.
7.
You collect data on the number of hours your classmates spend on social media daily and find that the data forms a bell-shaped curve. What can you infer about the data distribution?
Correct Answer
A. The data is normally distributed.
Explanation
If the data forms a bell-shaped curve, you can infer that "the data is normally distributed." A bell-shaped curve, also known as a Gaussian or normal distribution, is symmetrical, with the mean, median, and mode all located at the center. The normal distribution has the following characteristics:Symmetry: The left and right halves of the curve are mirror images of each other, indicating that the data is not skewed to the left or right.Central tendency: The mean, median, and mode are all located at the center of the distribution.Variability: The standard deviation determines the width of the bell curve, with a smaller standard deviation resulting in a narrower curve and a larger standard deviation resulting in a wider curve.In a normal distribution, approximately 68% of the data points lie within one standard deviation from the mean, 95% lie within two standard deviations, and 99.7% lie within three standard deviations. This characteristic makes the normal distribution a common model in statistics and data analysis.
8.
A group of 420 college students are enrolled in a blind test. The schools food service wants to see if they can improve the taste of their lattes. They decide to try two types of coffee beans (Aracabia and Robusta); three types of syrup (vanilla, hazelnut, and mocha); and two types of milk (soy and low fat). The best combination of ingredients is sought. The latte experiment will have
Correct Answer
E. 3 factors, 7 levels and 12 treatments
Explanation
E- The correct answer is E because three factors (coffee, syrup, milk), 7 levels (2 choices of coffee, 3 choices of syrup, 2 choices of milk), and 2x3x2= 12 combinations
9.
You want to do a survey of members of the senior class at your school and want to select a simple random sample. You intend to include 40 students in your sample. Which is the following approaches will generate a simple random sample?
Correct Answer
A. Write the name of each student in the senior class on a slip of paper and put the papers in a container. Then randomly select 40 slips of paper from the container.
Explanation
A - in order for this to be an SRS, all samples of size 40 must be equally likely. None of te other choices do this, and choice D isn't even random!
10.
Your company has developed a new treatment for acne. You think men and women might react differently to the medication, so you separate them into two groups. Then the men are randomly assigned to two groups and the women are randomly assigned to two groups. One of the two groups is given the medication and the other is given a placebo. The basic design of this study is
Correct Answer
B. Comparative randomized, blocked by gender
Explanation
B - you block men and women into different groups because you are concerned that differential reactions to the medication may confound the results. It is not completely randomized because it is blocked.
11.
A student organization wants to assess the attitudes of students towards a proposed change in the hours the library is open. They randomly select 50 freshmen, 50 sophomores, 50 juniors, and 50 seniors to survey. This situation is described as
Correct Answer
A. Stratified random sample
Explanation
A- since students are divided into strata by grade, this is a stratified random sample
12.
A television station broadcast a court trial in its entirety. During a news program, viewers were asked to go to the TV station’s website and state whether they thought the defendant was guilty or not guilty. Of the 1,840 viewers who gave their opinion, 1,521 felt that the defendant was not guilty. The viewers who registered their opinions constitute
Correct Answer
B. A voluntary response sample
Explanation
B, the only participants are the people who choose to respond. Usually end up with biased results because it attracts people with a strong opinion about a particular topic
13.
Melanie bakes two identical batches of cookies from a recipe, except one batch is made with sugar and the other batch is made with a sugar substitute. She puts the two batches of cookies into identical jars labeled “A” and “B.” She invites her friends to sample each type of cookie and to choose which cookie tastes best. What type of experimental design has she used?
Correct Answer
B. Single-blind design
Explanation
B, Melanie knows which type of cookie is in each jar, but her friends do not. This is the definition of a single-blind experiment: the researcher knows who is getting which treatment, but the subjects do not know.
14.
What type of sampling method is used when you select every 10th item from a list to create a sample?
Correct Answer
B. Systematic Sampling
Explanation
Systematic sampling involves selecting items at regular intervals (in this case, every 10th item) from a list or population.
15.
You want to determine if there's a relationship between the amount of exercise people do and their cholesterol levels. What type of statistical test is most suitable for this analysis?
Correct Answer
D. Correlation Analysis
Explanation
Correlation analysis is used to determine the strength and direction of the relationship between two continuous variables, such as exercise and cholesterol levels. It assesses if there's a statistical association between these variables.