Answer:
The correct word to use in the fill in the blanks´ question here would be the same: differences. As such, the full answer would be: Random assignment minimizes differences between experimental and control groups. Random sampling minimizes differences between the sample and a population.
Explanation:
In research, of any kind, especially when it has to do with experimentation, one central point is the selection of the participants and also, how they will be placed into the different groups that will be necessary, according to the objective of the study. Randomization is basically an insurance policy against bias, and it ensures that a study is applying objectivity while seeking the answers to a thesis. Using this randomization then ensures that there is little bias in the selection and appointment of participants into the different groups and in turn this ensures a minimization of differences between the groups. No one group will be favored due to a lack of objectivity in selection.
