Chapter I Introduction to Statistics _ statistics

1 statistics and its application fields

The methods used in data analysis can be divided into descriptive statistic method and inference statistic method.
Descriptive statistics: Research data collection, processing, summary, icon description, generalization and analysis of statistical methods
Inference statistics: A statistical method for studying how to use sample data to infer general features 2 types of statistical data

According to the different measurement scale, the statistic data can be divided into classified data, sequential data and numerical data. Classification data is disorderly such as men and women, enterprises by industry division, etc. sequential data is ordered non-numeric data, such as goods, second-class products, etc.
According to the method of collecting statistical data, it can be divided into observation data and experimental data. The difference is that there is nobody for control condition.
According to the relationship between the described phenomenon and time, it can be divided into cross section data and time series data.
Section data: Data collected at the same or approximately the same point in time, which is usually obtained in a different space to describe the change in the phenomenon at a given moment. For example, the GDP data of China's regions in 2005 are cross-section data.
Time series data: Data collected at different times
It is important to distinguish between types of data, and different methods should be used to deal with and analyze different types of data.
For the classification data, the frequency of each group is calculated and the ratio of the number and the χ2 is calculated, and the table is analyzed and the test is carried out.
For sequential data, calculate the number of digits and the four-point difference, calculate the grade correlation coefficient, etc.
Several concepts in the numerical data, the statistics of each group, the parameter estimation and the test 3 statistics

Overall: The collection of all the individuals (data) studied
Sample: A collection of elements extracted from the population
Parameters: A general numerical measure used to describe the overall feature, such as the overall average, the overall standard deviation, the overall ratio, etc.
Statistics: A general numerical measure used to describe the characteristics of a sample, such as sample averages, sample standard deviations, sample ratios, etc.
Variable: The concept of a characteristic of a phenomenon, such as the sale of goods, the level of education, etc. It can be divided into classified variables, sequential variables and numerical variables.