Which of the following is one of the changes detected by a polygraph?

Where records exist, in every Western country there has been a downward trend in the age of menarche. This trend is known as the ____

secular trend || lowering trend || premature menarche || early-onset trend || || ||

After defining the variables involved in a study, scientists have to identify individuals to study. The population is the group of individuals to whom we hope our conclusions will apply. Researchers generally hope that their conclusions will apply to a large population, such as all 20-year-olds in the country. Because it is not practical to examine everyone in the population, researchers study a

sample of people and assume that the results for the sample apply to the whole population. Briefly define the following types of samples: convenience sample, representative sample, random sample, and cross-cultural sample. What will be an ideal response?