Sampling Methods and Design Flashcards

A poll reports a 95% confidence interval of 42% ± 3%. What does this mean?

Answer: There is a 95% chance the true population value is between 39% and 45%

A 95% confidence interval means we are 95% confident the true population parameter falls within the stated range.

Which of the following is an example of voluntary response bias?

Answer: An online poll that only counts responses from people who choose to participate

Voluntary response bias occurs when participation is self-selected, typically attracting people with stronger opinions.

In proportional stratified sampling, sample sizes within each stratum are determined by:

Answer: Each stratum's proportion of the total population

Proportional stratified sampling allocates sample members based on each stratum's relative size in the population.

A researcher measures the same group of students at three different time points over two years. This design is called:

Answer: Longitudinal

A longitudinal design follows the same participants over time, enabling the study of changes and development.

What is the primary risk of using a very small sample size?

Answer: Higher probability of a Type II error and unreliable estimates

Small samples have low statistical power, increasing the chance of missing true effects and producing unstable estimates.

Researcher A surveys people at a mall on a Tuesday morning. What is the main sampling bias concern?

Answer: Undercoverage of people who are not at the mall on weekday mornings

Mall-intercept sampling on weekday mornings excludes working adults, systematically underrepresenting a large segment of the population.

A double-blind experiment is one in which:

Answer: Neither participants nor assessors know who received which treatment

In a double-blind design, both participants and those evaluating outcomes are unaware of group assignments, reducing bias.