validity, it is essential that the items or patients assigned to treatment and control groups be representative of the same population. In some experiments...

between treatment and control groups), difference in differences uses panel data to measure the differences, between the treatment and control group, of the...

Experimental design Scientific control Treatment and control groups Elliott SA, Brown JS. (2002). What are we doing to waiting list controls? Behav Res Ther. 2002...

characteristics that distinguish treatment and control groups are matched in an attempt to make the groups more alike. But if the two groups do not have substantial...

assigned to the treatment and units assigned to the control. In a randomized trial (i.e., an experimental study), the average treatment effect can be estimated...

subject to concerns regarding internal validity, because the treatment and control groups may not be comparable at baseline. In other words, it may not...

treatment or control groups to test claims of causal relationships. Random assignment helps establish the comparability of the treatment and control group...

{X_{i}}}-{\bar {X_{0}}}} , thus the differences between treatment groups' mean and control group's mean. This procedure ensures that the probability of all...

significant difference between the expected and actual ratios of the sizes of treatment and control groups in an experiment. Sample ratio mismatches also...

trials are used when there is a strong reason for randomising treatment and control groups over randomising participants. A 2004 bibliometric study documented...