Experimental Design and Sampling Practice

In a completely randomized experimental design, which of the following factors is most critical to ensure the validity of the results?

• The size of the control group

• The randomization process used to assign subjects to groups

• The number of variables being tested

• The duration of the experiment

Which of the following scenarios best illustrates the concept of random sampling in a population of 10,000 individuals?

• Selecting the first 100 individuals who volunteer for the study

• Using a computer program to randomly select 500 individuals from the entire population

• Choosing 200 individuals from a specific neighborhood

• Selecting individuals based on their last names alphabetically

When using stratified sampling, which of the following is a potential pitfall that researchers must avoid to ensure the sample is representative?

• Over-representing one stratum compared to others

• Using a small sample size

• Including too many strata

• Randomly selecting individuals within each stratum

Which type of bias is most likely to occur if a survey is conducted using only landline telephones in a population where many individuals use only mobile phones?

• Selection bias

• Response bias

• Non-response bias

• Measurement bias

In an experiment, why is it important to have a control group that is as similar as possible to the treatment group, except for the treatment itself?

• To increase the sample size

• To ensure that any observed effects are due to the treatment and not other variables

• To make the experiment easier to conduct

• To reduce the cost of the experiment

Which of the following is a key feature of a well-designed double-blind experiment?

• Only the participants are unaware of the treatment they receive

• Both the participants and the researchers are unaware of which group receives the treatment

• Only the researchers know which group receives the treatment

• The treatment is administered to all participants

What is the primary reason for using a placebo in a clinical trial?

• To deceive the participants

• To ensure that the treatment effect is not due to participants' expectations

• To reduce the cost of the trial

• To increase the number of participants

Which of the following best describes a potential drawback of systematic sampling?

• It is difficult to implement

• It may introduce bias if there is a hidden pattern in the population

• It requires a large sample size

• It is more expensive than other methods

In survey data collection, which of the following practices is most likely to introduce response bias?

• Ensuring anonymity of respondents

• Using neutral language in questions

• Asking leading questions that suggest a particular answer

• Randomly selecting participants

Which of the following best describes the cluster sampling method, and what is a potential risk associated with it?

• Dividing the population into clusters and randomly selecting entire clusters; risk of high variability between clusters

• Selecting individuals based on their availability; risk of convenience bias

• Randomly selecting individuals from each subgroup; risk of over-representation

• Selecting every nth individual from a list; risk of systematic bias