Final answer:
Including students from multiple states in research ensures the sample diversity and generalizability. A random sample is effective because it gives all individuals an equal chance to be selected, which reduces bias. Replicating findings across varying sample groups enhances a study's credibility.
Step-by-step explanation:
The importance of including students from multiple states in a research study lies in the aim to have a diverse participant pool that reflects different political views, social backgrounds, and features of various regions. This allows research findings to be more generalizable to a broader population.
In this context, the correct answer to the question would be 'd) To have participants from states or regions that traditionally have differing political views.' The inclusion of a diverse sample helps to ensure that research conclusions are not overly influenced by a homogenous group and that they reflect the complexities of a wider society.
Choosing a random sample is effective because it gives every individual within the population an equal chance of being selected for the study, thus minimizing selection bias. The correct answer for why a random sample is effective is 'd) Everyone has the same chance of being part of the study.'
Researchers trying to replicate findings adds to the credibility of the initial study, supporting the significance of the results across different sample groups, and therefore, makes the findings more robust and widely applicable.
Concerning the varying conclusions drawn by two researchers about the hours students spend playing video games, it cannot be determined who is correct without additional data. Valid conclusions require methodologically sound research, which includes a representative sample size and an appropriate data collection process.