GENERAL KNOWLEDGE

Detailed explanation-1: -In the Solomon four-group design, the researcher uses four groups. Two groups are treated as they would be in a classic experiment-pretest, experimental group intervention, and posttest. The other two groups do not receive the pretest, though one receives the intervention. All groups are given the posttest.

Detailed explanation-2: -Four major design types with relevance to user research are experimental, quasi-experimental, correlational and single subject. These research designs proceed from a level of high validity and generalizability to ones with lower validity and generalizability.

Detailed explanation-3: -Random assignment refers to a condition in which the participants of a study have an equal probability of being chosen for the experimental and control groups. A-Participants are set to be randomly assigned when they have a fair chance of getting selected for either of the groups either control or experimental.

Detailed explanation-4: -Random assignment is a key part of experimental design. It helps you ensure that all groups are comparable at the start of a study: any differences between them are due to random factors, not research biases like sampling bias or selection bias.