Assessment: To help assess student learning in her developmental math courses, a mathematics professor at a community college implemented pre- and posttests for her students. A knowledge-gained score was obtained by taking the difference of the two test scores.

(a) What type of experimental design is this?

Randomized design.

Step-by-step explanation:

Randomization is the process of assigning the treatments or tested factors to the experimental units in an experiment in accordance to definite laws or probability is technically known as randomization.

A randomized design relies on randomization to control for the effects of extraneous variables.

In a randomized design, objects or subjects are assigned to groups completely at random. One standard method for assigning subjects to treatment groups is labelling each subject and afterwards, using a list of random numbers to select from the labelled subjects. It is used when the experiment has treatment conditions and subjects. Also, subjects are randomly assigned to different treatments.

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