概率（probability），在心理学统计中，指从某个总体中得到特定的样本的可能性，是联系总体和样本之间的纽带。 in psychological statistics, refers to the likelihood of obtaining a specific sample from a population, serving as the link between the population and the sample.

• 为了得出正确的概率，在选取个体的过程中必须做到 随机取样 。
• To obtain accurate probabilities, random sampling must be employed during the selection of individuals.

• 随机取样应满足下述两个条件：
• Random sampling should satisfy the following two conditions:
• （1）总体中的每一个样本都有同样的机会被选择到；
• Every sample in the population should have an equal chance of being selected.
• （2）如果样本需要选择两个或以上的个体，那么每次做出选择时选出某一个体的概率都应该是相同的。
• If multiple individuals need to be selected for a sample, the probability of selecting any individual should be the same each time a selection is made.

• 要满足条件（2）就必须做到回置取样（sampling with replacement），即每次选择之前都应将之前取出的样本放回总体中。
• To fulfill condition (2), sampling with replacement must be implemented, meaning that each time a selection is made, the previously selected samples are placed back into the population.