Scientific-experimental evaluation, the most common type of evaluation design, is standard within the social sciences. These designs emphasize accuracy and impartiality. A control group and an independent variable allow researchers to test experiments in the most unbiased way. Experiments should be tested a number of times to come closer to a concrete theory for accurate results.
A process evaluation takes an in-depth look at a subject. It carefully documents early known facts and events about a topic and then compares those to the current situation. For example, an evaluation of teen pregnancy in a specific area might look at levels of those pregnancies dating back 10 years or more and compare those numbers to present rates. Whether mothers chose adoption or to raise the children themselves might also be examined.
Product evaluations serve to analyze the quality of a product as well as other factors such as demand, performance, and durability. Focus groups and customer feedback are used in some product evaluations. The safety of a product is also tested during a product evaluation. If a company manufactures a product but has two slightly different variations, it may test the two against one another to determine which variation is safer or more durable.