Designing Studies: Chapter 4 and 5 Notes

A researcher aims to understand the effects of a new fertilizer on crop yield. They randomly assign different fields to receive either the new fertilizer or the standard fertilizer. What type of study is this?

Which of the following is a key characteristic that distinguishes an experiment from an observational study?

In a study examining the relationship between smoking and lung cancer, researchers compare individuals diagnosed with lung cancer ('cases') to a group of similar individuals without lung cancer ('controls'). What type of observational study is this?

A researcher wants to investigate the long-term effects of regular exercise on cardiovascular health. They recruit a group of adults and track their exercise habits and cardiovascular health indicators over a 10-year period. What type of observational study is this?

What is the purpose of randomization in a well-designed experiment?

A researcher is conducting an experiment to test the effectiveness of a new drug. To minimize bias, neither the participants nor the researchers know who is receiving the actual drug and who is receiving a placebo. What experimental technique is being used?

In an experiment comparing the effectiveness of two different teaching methods, students are first grouped into blocks based on their prior academic performance. Then, within each block, students are randomly assigned to one of the two teaching methods. What experimental design is being used?

Which of the following experimental designs is particularly useful for controlling variability when comparing two treatments on highly similar experimental units?

What is the primary goal of sampling in statistical studies?

Which of the following sampling methods gives every individual in the population an equal chance of being selected and ensures that every possible sample of a given size has an equal chance of being selected?

A researcher wants to survey students about their opinions on a new campus policy. To ensure representation from all academic disciplines, the researcher divides the student population into subgroups based on their major (e.g., engineering, humanities, sciences) and then takes a separate simple random sample from each subgroup. What sampling method is being used?

A school district wants to assess student satisfaction with the quality of school lunches. They randomly select five schools from the district and then survey all students within those selected schools. What sampling method is being used?

A polling organization sends out a survey via email, and individuals can choose whether or not to respond. What type of sample is this?

What type of bias occurs when some groups in the population are systematically excluded from the sample?

In a survey about sensitive topics, such as personal income or drug use, what type of bias is most likely to occur when participants provide inaccurate or untruthful responses to appear more socially acceptable?

A researcher conducts a survey and finds that a significant portion of the individuals selected for the sample do not participate. If those who do participate differ systematically from those who do not, what type of bias is likely to occur?

Which of the following is a measure of the uncertainty associated with a sample estimate, indicating how much the estimate is likely to vary from the true population value?

What generally happens to the margin of error as the sample size increases?

Why do different samples from the same population produce different results?

What is a potential consequence of undercoverage in sampling?

Which of the following is a critical consideration regarding the wording of questions in a survey?

A researcher wants to study the average height of adults in a city. They randomly select 100 adults from a local gym. What type of bias is most likely to affect this study?

A company wants to gather feedback on a new product. They post a survey link on their social media page and encourage customers to participate. What is the most significant concern with this sampling method?

In an experiment to test a new weight loss drug, participants are weighed at the beginning of the study, then given the drug (or a placebo). They are weighed again after 8 weeks. What is the purpose of weighing the participants at the beginning of the study?

A researcher is studying the effect of different fertilizers on tomato yield. The researcher has access to 20 tomato plants of varying sizes. To account for the initial size differences, what study design should the researcher employ?

A public health official wants to assess the prevalence of flu in a city. They randomly select several neighborhoods and test every person in those neighborhoods for the flu. What sampling method are they using?

When designing an experiment to test the effect of a new teaching method on student test scores, what is the primary reason for including a control group?

A newspaper publishes an online poll asking readers to vote on their favorite candidate for mayor. What type of sampling method is being used, and what is its primary limitation?

An experiment is designed to investigate the effect of caffeine on reaction time. Participants are given either a caffeinated beverage or a decaffeinated beverage, and their reaction time is measured. What is the purpose of using a decaffeinated beverage in this experiment?

What are studies?

Observational Studies

Surveys

Case-control studies

Cohort studies

Experiments

Elements of Well-Designed Experiment

Completely Randomized Design

Randomized Block Design

Matched Pairs Design

Placebo effect

Blinding

Sampling

Population

Sample

Voluntary Response Sample

Convenience Sample

Simple Random Sample (SRS)

Stratified Random Sample

Cluster Sample

Systematic Sample

Bias

Selection bias

Nonresponse bias

Response bias

Statistical inference

Margin of error

Sampling Variability

Undercoverage

Nonresponse