1.11: 随机抽样方法

Random Sampling Method
JoVE Core
Statistics
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JoVE Core Statistics
Random Sampling Method

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01:09 min
April 30, 2023

Overview

Sampling is a technique to select a portion (or subset) of the larger population and study that portion (the sample) to gain information about the population. Data are the result of sampling from a population. The sampling method ensures that samples are drawn without bias and accurately represent the population. Because measuring the entire population in a study is not practical, researchers use samples to represent the population of interest. Among the various sampling methods used by researchers, the random sampling method is a commonly used sample collection method. Here, each member of the population has an equal chance of being selected.

For example, let us see how a random sampling method can determine the mean number of college professors' books in their offices in a particular college. Suppose 25 professors are randomly selected and asked about the number of books in their office. The data obtained shall give a statistical result of the number of books owned by each professor in the entire college. Another example is determining the average cost of a two-day stay in a hospital in Massachusetts by conducting surveys of 100 hospitals across the state, selected using simple random sampling.

The probability sampling method is similar to random sampling but has significant differences. The probability of selection of each member of the population is known but not necessarily the same. Suppose a college has 10,000 part-time students (the population). To determine the average amount of money a part-time student spends on books in the fall term, the probability sampling method can be used. A sample of 100 different part-time students from the ten disciplines is randomly selected such that at least one student from each discipline is sampled. Several students from each discipline being selected has a fixed but not necessarily an equal chance of being selected. This is an example of the probability sampling method.

This text is adapted from Openstax, Introductory Statistics, Section 1.2 Data, Sampling, and Variation in Data and Sampling

Transcript

抽样方法用于从总体中抽取样本,确保抽样时没有偏差,并且能够准确代表总体。

随机抽样法是一种常用的样本采集方法。在这里,种群的每个成员都有相等的机会被选中。

考虑一个装有 20 个塑料球的容器,每个塑料球有 5 个塑料球,每个球有四种不同的颜色——红色、黑色、蓝色和绿色。

如果从盒子中随机拿起一个球,则 20 个球中有 5 个或 4 个球中有 1 个是红色、黑色、蓝色或绿色的几率。因此,每种颜色都有相同的机会被选中。

概率抽样方法与随机抽样类似,但有一个显著差异。种群中的每个成员都有已知的(但不一定相同)被选中的机会。

假设同一个盒子里装满了不同数量的彩球。每个彩球都有固定但不一定相等的被选中机会。

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