2, the value of m is average, arithmetic average.

Arithmetic average, also called average, is the most basic and commonly used average index in statistics, which can be divided into simple arithmetic average and weighted arithmetic average. Mainly suitable for numerical data, not for quality data. According to the different forms of expression, the arithmetic mean has different calculation forms and formulas.

Arithmetic average is a special form of weighted average (especially in equal weight). In practical problems, when the weights are not equal, the weighted average should be used when calculating the average; When the weights are equal, the arithmetic average is used to calculate the average.

3. SD value is the standard deviation of the mean, which is a statistic describing the discrete distribution of a group of variables.

The standard deviation is the arithmetic square root of the arithmetic mean (i.e. variance) of the mean square deviation, and is expressed by σ. Standard deviation, also known as standard deviation, or experimental standard deviation, is most commonly used as the measurement basis of statistical distribution in probability statistics.

The standard deviation is the arithmetic square root of variance. The standard deviation can reflect the degree of dispersion of the data set. The standard deviation of two sets of data with the same average value may be different.

Extended data:

Application of standard deviation:

Standard deviation is the most commonly used measure of statistical distribution in probability statistics. The standard deviation is defined as the square root of the arithmetic mean of the deviation square of the standard value of each unit from its average value. It reflects the degree of dispersion among individuals in a group. The result of measuring the distribution degree has two properties in principle:

Is non-negative, and the unit is the same as the measured data. There is a difference between the standard deviation of a population or random variable and the standard deviation of the number of samples in a subset.

Simply put, the standard deviation is a measure of the deviation of the average value of a set of data. The standard deviation is large, indicating that most of the values are quite different from their average values; A smaller standard deviation means that these values are closer to the average.