Question

1. How do the three criteria for an experimental design, manipulation, randomization, and control minimize bias and decrease threats to internal validity?

2. Why do researchers state that randomized clinical trials provide the strongest evidence for an individual study when using an evidence-based model?

3. How does intervention fidelity increase the strength and quality of the evidence provided by the findings of a study using these types of designs?

Answer 1

1.In experimental design,some subjects are administered experimental design one or more stimulus ,that is treatment group,and the other group not giving stimulus called control group.The experimental design may be supposed to be successful if the subjects in the treatment group rate more than the control group.Treatment manipulation helps control for the cause,in cause effect relationship.The success of experimental design related to how well the treatment was manipulated.Randomization is the process of selecting a sample from a population immediately without giving much information to the population.This approach mainly used in survey.This tratmtrea assures every single people in the population have chance of getting selection.Thus the three concepts decrease threats to internal validity.

2.Ranfom selection is a process of randomly selecting subjects to experimental or control groups.This practice is generally acceptable in true experimental research to ensure that the treatment groups are similar to each other and to the control group, before the treatment.

3.In experimental design,one or more variables are manipulated by the researchers as treatments, subjects are selected immediately bto different treatment levels that is random assignment,and the results of the treatment s are observed.The unique streangth of experimental research is its internal validity due to its ability to link cause and effect through treatment manipulation.