Sampling Methods and Bias in Surveys

The video tutorial covers the importance of random sampling in statistics and the challenges associated with it, such as bias and practicality. It uses Delilah's survey as a case study to illustrate the limitations of convenience sampling. The tutorial also discusses various sampling methods, including random and stratified sampling, and their potential biases. Finally, it analyzes a health study on aspirin use, highlighting the importance of understanding the sample population when drawing conclusions.

Why is random sampling considered important in statistics?

• It always provides accurate results.

• It is easier to implement than other methods.

• It closely represents the population from which it is drawn.

• It eliminates the need for data analysis.

What is a major drawback of convenience sampling?

• It is too expensive to conduct.

• It often leads to invalid claims about the population.

• It requires a large sample size.

• It is time-consuming to implement.

In Delilah's survey, what was a key limitation of her sampling method?

• She surveyed only people who do not vote.

• She surveyed only voters from a single grocery store.

• She surveyed only people who shop online.

• She surveyed only people who work at night.

How can Delilah improve her sampling technique to better represent American voters?

• Survey at different times and locations.

• Only survey people with children.

• Survey only in her town.

• Survey only during weekends.

What is a common bias in call-in surveys on morning TV shows?

• They only reach people who work night shifts.

• They only reach people with no strong opinions.

• They only reach people with strong opinions and flexible schedules.

• They only reach people who are not interested in the topic.

Why might mailed questionnaires lead to biased results?

• They are only sent to people who request them.

• They are only answered by people who feel strongly about the topic.

• They are only answered by people who dislike surveys.

• They are only sent to people with internet access.

What is a potential bias when surveying students on a school bus about education funding?

• Students may not understand the survey questions.

• Students may be biased towards supporting more funding.

• Students may not have time to complete the survey.

• Students may not be interested in education policies.

What was the main finding of the aspirin study on male physicians?

• Aspirin has no effect on heart attacks.

• Aspirin increases the risk of heart attacks.

• Aspirin reduces heart attacks for male physicians aged 40 to 84.

• Aspirin reduces heart attacks for all people.

Can the results of the aspirin study be generalized to all men aged 40 to 84?

• Yes, because all men have similar health conditions.

• Yes, because the sample size was large.

• No, because the study only included male physicians.

• No, because the study was conducted over a short period.

Why should caution be exercised before recommending aspirin to male physicians aged 40 to 84?

• The study did not include any control group.

• The study only included a small number of participants.

• The side effects of aspirin were not fully explored.

• The study was not conducted by qualified researchers.