Professional Knowledge for Junior Statisticians in 217: Number and Distance of Groups

the relationship between class data and class width (I) is that i=R/m changes inversely

2. Isometric grouping and isometric grouping

When the changes of objective phenomena are relatively balanced, isometric grouping should be adopted

When the changes of objective phenomena are not balanced, It is appropriate to use different distance grouping

3. classlimit and class midpoint

Group limit is the interval endpoint (including upper limit and lower limit) of each grouping

The median value in the group, that is, the midpoint value between the upper limit and lower limit, is called group median

1. Total index is also called quantitative index, which reflects the total scale, level or total work of social and economic phenomena. Total index is an important basis for making plans, formulating policies and implementing scientific management; The gross index is the basis of calculating relative index and average index.

2. Types of gross indicators

① Gross indicators are divided into total unit gross and total sign gross according to the overall content of the phenomenon.

the total unit amount is the sum of the total number of units, and the total mark amount is the sum of the mark values of each unit.

② Total indicators can be divided into period indicators and time indicators according to the different time conditions reflecting phenomena.

the period indicator is the total indicator reflecting the development and change results of social and economic phenomena in a period of time, which is obtained by continuously registering data, such as the total industrial output value and commodity sales. Time-point index is a total index reflecting the social and economic phenomena at a certain moment, such as population, land area, commodity inventory and so on.

There are three main differences between period indicators and time-point indicators: one is continuous statistics of period indicators and intermittent statistics of time-point indicators; Second, the period index values can be accumulated, but the direct accumulation of the time index values has no practical significance; Third, the numerical value of period index is related to the length of statistical period, while the numerical value of time index is not directly related to the length of time interval.

③ Total indicators are divided into physical indicators, value indicators and labor measurement indicators according to different units of measurement.

Physical indicators are total indicators measured in natural units, units of measurement or composite units, which are intuitive and specific, but physical indicators of different units of measurement cannot be summarized; Value index is a total index measured in monetary unit, which has extensive comprehensive and generalization ability, but it is abstract; Labor quantity index is a total index measured by labor time, working hours and working days, which is convenient for internal assessment and management of enterprises.