front 1 Observational study | back 1 observes individuals and measures variables of interest but does not attempt to influence the responses. |
front 2 Experiment | back 2 deliberately imposes treatments (conditions) on individuals to measure their responses |
front 3 Response variable | back 3 Measures an outcome of a study |
front 4 explanatory variable | back 4 may help explain or predict changes in a response variable |
front 5 confounding | back 5 occurs when two variables are associated in such a way that their effects on a response variable cannot be distinguished from each other. |
front 6 treatment | back 6 a specific condition applied to the individuals in an experiment |
front 7 placebo | back 7 a treatment that has no active ingredient, but is otherwise like other treatments |
front 8 experimental unit | back 8 the object to which the treatment is randomly assigned |
front 9 Subject | back 9 experimental units that are human beings. |
front 10 factor | back 10 an explanatory variable that is manipulated and may cause a change in the response variable |
front 11 levels | back 11 different values of a factor |
front 12 control group | back 12 used to provide a baseline for comparing the effects of other treatments in an experiment |
front 13 placebo effect | back 13 describes the fact that some subjects in an experiment will respond favorably to any treatment, even an inactive treatment. |
front 14 random assignment | back 14 Experimental units are assigned to treatments using a chance process. |
front 15 control | back 15 keeping other variables constant for all experimental units |
front 16 replication | back 16 giving each treatment to enough experimental units so that a difference in the effects of the treatments can be distinguished from chance variation due to random assignment |
front 17 Completely randomized design | back 17 the experimental units are assigned to the treatments completely at random |
front 18 Double blind | back 18 neither the subjects nor those who interact with them and measure the response variable know which treatment a subject is recieving |
front 19 Single blind | back 19 either the subjects or the people who interact with them and measure the response variable don't know which treatment a subject is receiving |
front 20 Block | back 20 a group of experimental units that are known BEFORE the experiment to be similar in some way that is expected to affect the response to the treatments |
front 21 Randomized block design | back 21 the random assignment of experimental units to treatments is carried out separately within each block |