Which of the following is important to ensure that a study has statistical validity?

• A. Reporting only the results that confirm the researcher's expectations
• B. Increasing the sample size without regard to sampling method
• C. Using a random sample from the population of interest
• D. Selecting only participants who are likely to support the hypothesis

Answer: (C)

Verified step by step guidance

1. Understand that statistical validity refers to the extent to which the conclusions drawn from a study are accurate and reliable, particularly in representing the population of interest.
2. Recognize that using a random sample from the population is crucial because it ensures that every member of the population has an equal chance of being selected, which helps to avoid bias.
3. Note that reporting only results that confirm expectations introduces bias and undermines the validity of the study by ignoring contradictory evidence.
4. Understand that increasing sample size alone does not guarantee validity if the sampling method is flawed; the sample must be representative of the population.
5. Realize that selecting only participants who support the hypothesis leads to a biased sample and invalid conclusions, so it is important to avoid this practice.