Question 1

What does the term "bias" mean in research studies? Choose the best answer.

Accepted Answer

Bias in research studies refers to a systematic error that can occur due to various factors such as faulty study design, data collection methods, or analysis techniques, which can lead to incorrect conclusions.

Question 2

The difference between the estimated and actual value of a variable for three cases were as follows: -3, +9, +2. What type of error do these differences suggest?

Accepted Answer

These differences suggest random error because they vary in both direction and magnitude, indicating that the errors do not consistently skew in one direction (which would suggest bias) and are not necessarily related to measurement inaccuracies or variance issues.

Question 3

What is a cross-sectional study?

Accepted Answer

A cross-sectional study is characterized by data being collected at a single point in time, allowing researchers to examine a snapshot of whatever phenomenon or population they are studying.

Question 4

In a study on changes in weather patterns in Buffalo, NY, temperatures were recorded for each month, using a sample of 10 zip codes. The process of recording temperature per month was repeated every 5 years for a different sample of 10 zip codes. The data covered a total time period of 20 years. What type of research study is this?

Accepted Answer

This is a repeated cross-sectional study because it involves taking multiple snapshots over time (every 5 years) with different samples (different zip codes each time) to observe changes in weather patterns. Unlike a longitudinal study, which follows the same subjects over time, this approach samples different subjects (zip codes) at each time point.

Question 5

What does the term "cohort study" refer to?

Accepted Answer

A cohort study specifically refers to research that follows a group of people over time who share a common characteristic or experience within a defined period. This allows for the examination of how certain factors affect outcomes over the long term.

Question 6

A study collects data for a set of individuals, on a common set of variables, over multiple periods of time. Which term best describes this type of study?

Accepted Answer

The answer of A study collects data for a set...

Question 7

Which of the following statements is true of a case-control study?

Accepted Answer

Case-control studies involve comparing individuals with a particular condition or disease (cases) to individuals without the condition (controls), to identify factors that may contribute to the presence of the disease.

Question 8

A study identified a sample set of 200 policyholders who had either one or no motor vehicle incidents in the last 2 years. The characteristics of this set of policyholders was analyzed in the study. What type of bias does the study suffer from?

Accepted Answer

The answer of A study identified a sample set of...

Question 9

A researcher designs a study on political affiliations of those residing in Mercer county, New Jersey. A sample set of households were chosen who resided mainly in and around the town of Princeton. Which type of bias is present in this study design?

Accepted Answer

The study likely suffers from sample selection bias because it does not represent the entire population of Mercer County, focusing instead on households primarily in and around Princeton, which may not reflect the political affiliations of the broader county population.

Question 10

What is a "sampling frame"?

Accepted Answer

A sampling frame is essentially a list or database that includes all the elements in the population from which the sample will be drawn, ensuring that every element has a chance to be included in the sample.

Question 11

A random sample of 2,000 units is chosen from a data set of 49,000 elements. What is the probability of selection to the sample?

Accepted Answer

The probability of selection is calculated by dividing the number of units chosen (2,000) by the total number of elements in the data set (49,000), which equals approximately 0.041 (or 4.1%).

Question 12

A study on political affiliations of residents of Mercer county, New Jersey, created random samples of 100 residents from each census tract within the county. The samples of 100 were then combined to create a master sample for the study. What is this type of sample called?

Accepted Answer

This is stratified random sampling because the population is divided into strata (census tracts), and random samples are taken from each stratum.

Question 13

Which primary factor distinguishes cluster sampling from stratified sampling?

Accepted Answer

The answer of Which primary factor distinguishes cluster sampling from...

Question 14

What does the term "matching" mean in case-control studies?

Accepted Answer

The answer of What does the term "matching" mean in...

Question 15

Which are the nonprobability methods of sampling?

Accepted Answer

Nonprobability sampling methods include convenience, quota, and case-control because they do not give all members of the population an equal chance of being selected.

Question 16

A research study on the quality of customer service of telecom call centers, chose 20 call centers for the study, with the condition that at least four had to be from Pakistan, two had to be selected from Ireland, and, another four were to be from the Philippines. What type of sampling method was used by this study?

Accepted Answer

The study used a quota sampling method because it specified a certain number of call centers to be selected from predetermined groups (Pakistan, Ireland, and the Philippines), ensuring that each group was represented in the sample.

Question 17

What is "selective observation" in designing a research study?

Accepted Answer

Selective observation involves choosing only those cases or data points that support the hypothesis or expectations of the researcher, leading to biased results.

Question 18

What does the term "differential nonresponse" refer to?

Accepted Answer

Differential nonresponse refers to the phenomenon where certain groups or individuals with specific characteristics are less likely to respond to a survey or study, leading to potential bias in the results.

Question 19

A survey questionnaire was sent to 1,000 individuals. 456 of those individuals filled out and returned the questionnaire. What is the nonresponse rate of this survey?

Accepted Answer

The nonresponse rate is calculated by subtracting the response rate from 100%. In this case, 456 out of 1,000 individuals responded, so the response rate is 45.6%. Therefore, the nonresponse rate is 100% - 45.6% = 54.4%.

Question 20

What are the consequences of attrition to a longitudinal study?

Accepted Answer

Attrition in a longitudinal study leads to a decreasing sample size as participants drop out over time.

Quiz 11: Bias