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Stats Ch 10
| Term | Definition |
|---|---|
| Observational Study | A study based on data in which no manipulation of factors has been employed. |
| Retrospective Study | A type of observational study in which subjects are selected and then their previous conditions are determined. |
| Prospective Study | A type of observational study in which subjects are followed to observe future outcomes. |
| Experiment | A study that manipulates factor levels to create treatments, randomly assigns subjects to these treatment levels, and then compares the responses of the subject groups across the treatment levels. |
| Random Assignment | Experimental units are randomly assigned to treatment groups. |
| Factor | Levels are manipulated by the experimenter in an attempt to discover any effects it may have on the response variable. |
| Response | The value of a variable is compared across different treatments. |
| Experimental Units | Individuals on whom the experiment is performed (known as subjects or participants if human) |
| Level | The specific value that the experimenter chooses for a factor. |
| Treatment | The process/levels of factor applied to randomly assigned experimental units. |
| Statistically Significant | When an observed difference is too large for us to believe that it is likely to have occurred by chance. |
| Control Group | The experimental units assigned to baseline treatment level, or a placebo treatments and whose responses are the basis of comparison. |
| Blind | Any individual associated with an experiment who is not aware of how subjects have been allocated to treatment group. |
| Single-Blind | When either those who can influence the results or those who evaluate the results are not aware of how subjects have been allocated to the treatment group. |
| Double-Blind | When both those who can influence the results and those who evaluate the results are not aware of how subjects have been allocated to the treatment group. |
| Placebo | A treatment known to have no effect, administered so that all groups experience the same conditions. |
| Placebo Effect | The tendency that human subjects show a response even when administered a fake treatment. |
| Completely Randomized Design | All experimental units have an equal chance of receiving any treatment. |
| Blocking | Placing experimental units into groups based on pre-existing differences to isolate the differences to see the effects of the treatments more clearly. |
| Randomized Block Design | Subject are randomly assigned to treatments only within groups based on pre-existing differences. |
| Matching | In a retrospective or prospective study or experiment, subjects who are similar in ways not under study may be grouped and compared with each other on the variables of interest. |
| Confounding | Types of factors when the levels of one factor are associated with the levels of another factor in such a way that their effects cannot be separated. |
| Principles of Experimental Design | Control aspects we can, randomize to make up for aspects we can't, and replicate as many times as possible. |