Final answer:
It is false that researchers always use personal judgement to select subjects. Instead, researchers aim for objectivity using strategies like random sampling, but sometimes use convenience samples for practicality, which can have limitations. The selection of subject data should be justified methodologically, as noted by AP guidelines.
Step-by-step explanation:
It is false to assert that a researcher always uses his/her own judgement in choosing the subjects for a study. While a researcher's opinion and personal judgments could influence the selection of subjects, the goal in scientific research is to achieve objectivity and accuracy. Researchers must often rely on random sampling or other methodological strategies to select participants in order to minimize bias and to ensure the generalizability of the findings. However, there are occasions, such as when using a convenience sample like students enrolled in Introduction to Psychology courses, where researchers select participants due to practical considerations. In such cases, researchers should be transparent about the possible limitations and implications of their sampling technique, such as its potential to not accurately represent the larger population.
When researchers use a self-selected sample, they must be cautious because these samples may not be representative of the population. This is particularly true for responses from self-selected samples like internet surveys, which can be unreliable. Lastly, the AP guidelines indicate that students should be able to justify the selection of the kind of data needed to answer a particular scientific question, highlighting the importance of methodologically sound sampling procedures in research design.