10/06/28 16:56:31
>>285
おお…ありがとうございます…！そなたに心よりの感謝を!
そしてさらに4分の1を。俺…これが終わったら食事して仮眠を取るんだ…
One important feature of the experiment just described is random assignment of participants to groups or conditions.
Random assignment means that each participant has an equal probability of being placed in any group.
Without random assignment,the experimenter cannot be certain that something other than the independent variable might have produced the results.
For example,an experimenter should never let participants choose whici group they would like to be in.
Although most participants might choose to be in the highest-paid group,
those who are made nervous by pressure might choose to be in a“casual”group that was not paid.
In any case,the problem is that the groups would now contain different kinds of people,and the differences in their personalities,
rather than the amount of money offerd,might cause one group to do better than another.
Or suppose that an experimentr runs all the paid groups first and runs the no-payment control group afterward.
This introduces a host of potential problems.
Perhaps performance varies as a function of the time of day (morning,afternoon,or evening);maybe those
who participate later in the experiment are closer in time to their final exams than earlier participants.
In addition to these uncontrolled variables,many others of which the experimenter is unaware might bias the results.
All such problems are resolved by randomly assigning participants to conditions.
Only with random assignment can we be caertain that all extraneous variables―such as participant personality,time of day,
or time of semester―are evenly represented across conditions and therefore unlikely to introduce bias.
Random assignment is one of the most important ingredients of an experiment.