1.3 Sampling

Last updated over 1 year ago

5 questions

Required

Determine whether the given description corresponds to an observational study or an experiment

Cruise ship passengers are given magnetic bracelets, which they agree to wear in an attempt to eliminate or diminish the effects of motion sickness.
The Dutchess County Bureau of Weights and Measures randomly selects gas stations and obtains 1 gallon of gas from each pump. The amount pumped is measured for accuracy.
Much controversy arose over a study of patients with syphilis who were not given a treatment that could have cured them. Their health was followed for years after they were found to have syphilis.
Patients are given Lipitor to determine whether this drug has the effect of lowering high levels of cholesterol.

observational study
experiment

Required

Identify the type of observational study.

An economist collects data by interviewing people who won the lottery between the years of 1995 and 2000.
A researcher from Mt. Sinai Hospital in New York City plans to obtain data by following siblings of victims who perished in the World Trade Center terrorist attack of September 11, 2001.
A researcher from the New York University School of Medicine obtains data about head injuries by examining the hospital records from the past five years.
The U.S. Labor Department obtains current unemployment data by polling 50,000 people this month.

retrospective
cross-sectional
prospective

Required

Identify the Bias Type in each study

A survey about job satisfaction is conducted only among employees who use company email regularly.
In a survey, questions are ordered in such a way that early questions influence the responses to later questions. For example, if a survey on political views starts with questions about environmental issues, respondents may answer subsequent questions about political alignment in a way that aligns with their responses to the initial questions.
A survey on exercise habits is conducted at a gym, only including people who already go to the gym.
A company sends out customer satisfaction surveys to users of its service. Customers who are dissatisfied with the service may be more likely to complete and return the survey.
An opinion poll is conducted to gauge support for a political candidate. The poll is administered over the phone, but individuals who are not home or who do not answer calls from unknown numbers are less likely to participate.
During an in-person interview, a participant provides answers that they think the interviewer wants to hear, especially if the interviewer is seen as an authority figure or has a strong influence on the outcome.
A survey asks individuals about their exercise habits and overall health. Respondents may overstate their exercise frequency and healthy behaviors to present themselves in a more favorable light.
A survey about job satisfaction includes statements like "I am happy with my current job" with response options ranging from "Strongly Disagree" to "Strongly Agree." Respondents may be more likely to agree with statements regardless of their true feelings, particularly if they want to avoid conflict or appear agreeable.
A researcher studies the effects of a new drug but only includes participants who actively volunteer for clinical trials.
A survey was sent to College students about campus events.
An online survey about health habits is only shared on social media platforms, potentially excluding older adults who are less active online.

undercoverage
voluntary response bias
non-response
response bias

Required

Identify which type of sampling is used.

An economist is studying the effect of education on salary and conducts a survey of 150 randomly selected workers from each of these categories: less than a high-school degree; high-school degree; more than a highs-school degree.
The Dutchess County Commissioner of Jurors obtains a list of 42,763 car owners and constructs a pool of jurors by selecting every 100th name on that list.
A marketing executive for General Motors finds that its public relations department has just printed envelopes with the names and addresses of all Corvette owners. She wants to do a pilot test of a new marketing strategy, so she thoroughly mixes all of the envelopes in a bin, then obtains a sample group by pulling 50 of those envelopes.
Motivated by a student who died from binge drinking, the College of Newport conducts a study of student drinking by randomly selecting 10 different classes and interviewing all of the students in each of those classes.
A General Motors researcher has partitioned all registered cars into categories of subcompact, compact, mid-size, intermediate, and full-size. She is surveying 200 car owners from each category.
A Johns Hopkins University researcher surveys all cardiac patients in each of 30 randomly selected hospitals.
During the last presidential election, CNN conducted an exit poll in which specific polling stations were randomly selected and all voters were surveyed as they left the premises.
A marketing expert for MTV is planning a survey in which 500 people will be randomly selected from each age group of 10-19, 20-29, and so on.
In a Gallup poll of 1059 adults, the interview subjects were selected by using a computer to randomly generate telephone numbers that were called.
An observer noticed that at a police sobriety checkpoint, that every 5th driver was stopped and interviewed.
A statistics student obtains height/weight data by interviewing family members.
An NBC television news reporter gets a reaction to a breaking story by polling people as they pass the front of his studio.

convenience
random
systematic
stratified
cluster

Required

Identify which type of sampling is used.

In 1936, Literary Digest magazine mailed questionnaires to 10 million people and obtained 2,266,566 responses. The responses indicated that Alf Landon would win the presidential election. He didn't.
Your teacher collected data by randomly selecting 35 pages from your textbook and then counting the number of words on each of those pages.
The sexuality of women was discussed in Shere Hite's book Women and Love: A cultural Revolution. Her conclusions were based on sample data that consisted of 4500 mailed responses from 100,000 questionnaires that were sent to women.
In a study of treatments for back pain, 641 subjects were randomly assigned to the four treatment groups of individualized acupuncture, standardized acupuncture, simulated acupuncture, and usual care (based on data from "A Randomized Trial Comparing Acupuncture, Simulated Acupuncture, and Usual Care for Chronic Low Back Pain," by Cherkin et al., Archives of Internal Medicine, Vol. 169, No. 9)
In a Kelton Research poll, 1114 Americans 18 years of age or older were called after their telephone numbers were randomly generated by a computer, and 36% of the respondents said that they believe in the existence of UFOs/
Researchers randomly selected 50 convicted felons from each category of burglary, auto theft, and assult
Satellites are used to collect sample data for estimating deforestations rates. The Forest Resources Assessment of the United Nations (UN) Food and Agriculture Organization uses a method of selecting a sample of a 10-km wide square unit at every 1-degree intersection of latitude and longitude.
A Harris interactive study involved 1013 adults who were interviewed about washing their hands in restrooms and another 6336 adults were observed in public restrooms.
The New York State Department of Transportation evaluated the quality of the New York State Thurway by testing core samples collected at regular intervals of 1 mile.
In a clinical trial of the cholesterol drug Lipitor (atorvastatin), subjects were partitioned into groups given a placebo or Lipitor doses of 10mg, 20 mg, 40 mg, or 80 mg. The subjects were randomly assigned to the different treatment groups (based on data from Pfizer, Inc.)
Cormorant bird population densities were studied by using the "line transect method" with aircraft observers flying along the shoreline of Lake Huron and collecting sample data at intervals of every 20 km (based on data from Journal of Great Lakes Research)

convenience
random
systematic
stratified
cluster