We call the number of groups the number of groups, and the difference between the two endpoints of each group is called the group distance.

See also: number of groups

The difference between the maximum value and the minimum value (also called upper limit and lower limit) of each group when grouping according to the quantity mark in the variable sequence. The interval between groups can be equal, for example, workers are divided into three groups according to their age: 15-25, 25-35 and 35-45; The intervals between groups can also be unequal. For example, industrial enterprises are divided into three groups according to the number of employees: 30- 100, 10 1-200 and 20 1-350. The use of equal or unequal intervals between groups is generally determined by the requirements of statistical research and the different characteristics of phenomena.

absolute frequency

In a group of measured values arranged in order of size, the number of measured values appearing in each group when grouped at a certain group distance.

If there is a set of measured data, the total data is N= 148, the minimum measured value xmin=0.03, and the maximum measured value xmax=3 1.67. According to the interval △x=3.000, the data of 148 are divided into 1 1 groups, which are distributed in

For another example, in 3.14159265358979324, the frequency of' 9' is 3, and the frequency is 3/ 18= 16.7%.

Generally, we call the number of data in different groups the frequency of the group, and the ratio of frequency to the total number is the frequency.

frequency

Also called "times", the total data is grouped according to some standard, and the number of individuals in each group is counted. Frequency is the ratio of the frequency of each group to the total data.

In the variable distribution sequence, frequency indicates the function degree of the corresponding group flag values. The greater the frequency value, the greater the contribution of this group of flag values to the overall level; On the contrary, the smaller the frequency value, the smaller the contribution of this group of marker values to the overall level.