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...

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...

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...

mention of controls and can therefore describe studies that compare multiple treatment groups with each other in the absence of a control group. Similarly...

and age). PSM attempts to control for these biases by making the groups receiving treatment and not-treatment comparable with respect to the control variables...

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

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

specific treatment outcome for pedophiles. Many do not select their treatment and control groups randomly. Offenders who refuse or quit treatment are at...

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

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

focus is typically on the average treatment effect (the difference in outcomes between the treatment and control groups) or another test statistic produced...

experiments (see treatment and control groups) Sham surgery, surgery omitting the therapeutic component, performed in the single-blinded control group of experiments...

each of the treatment and control groups. The treatment group in the unpaired design would be viewed as analogous to the post-treatment measurements...

pre-treatment evaluation can be calculated by comparing the control group who received the pre-treatment evaluation with those who did not (groups 2 and 4)...

{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...

larger) between the treatment and control groups. For example, a trial of a lipid-lowering drug versus placebo with 100 patients in each group might have a power...

the comparison (control) group are affected by the intervention. Contamination occurs when members of treatment and/or comparison groups have access to...

organization, content, and so on. As more attributes are compared, it becomes increasingly likely that the treatment and control groups will appear to differ...

Placebo-controlled studies are a way of testing a medical therapy in which, in addition to a group of subjects that receives the treatment to be evaluated...

of the trial, in both the control and treatment groups nearly a fifth "died from diseases of poverty, gastroenteritis and pneumonia, as a result of the...

of a treatment variable of interest. For example, in a clinical study of a drug, the treated population may die at twice the rate of the control population...

of clinical study where two groups of treatments, A and B, are given so that one group receives only A while another group receives only B. Other names...

two groups at the same time: One group receives the treatment (the "treatment group") The other group does not get the treatment (the "control group")....

(non-treatment group) both produce a negative result, it can be inferred that the treatment had no effect. If the treatment group and the negative control...

in both groups. However, side effects are not the only cause of unblinding; any perceptible difference between the treatment and control groups can contribute...

secure a "mercy pass". This leads to selection bias, as the treatment and control groups now differ. In the latter case, some students may decide to retake...

Laupacis, Sackett and Roberts. While theoretically, the ideal NNT is 1, where everyone improves with treatment and no one improves with control, in practice...

momentary assessment Experiment, often with separate treatment and control groups (see scientific control and design of experiments). See Experimental psychology...

score between 0 and 100. The effectiveness of an intervention is usually based on comparison of these scores in treatment and control groups. It has been...