Mathematical modeling --- Use tools for descriptive statistics

Simple statistics

matlab

Excel

SPSS

Correlation coefficient

Spearman correlation coefficient

Mathematical Modeling-Spearman Correlation Coefficient

Pearson correlation coefficient

Mathematical modeling-Pearson correlation coefficient

Stata makes probability density estimation graph and saves the picture

// 做x的概率密度估计图
kdensity x

//保存图片
graph export a.png ,replace

Stata's descriptive statistics on data

Quantitative data

summarize  变量1 变量2 ... 变量n

• If you put it in the paper, you need to put it in Excel first to become a three-line table, and then put the three-line table in the paper

summarize 变量 ,d

• Percentiles
  said that the data corresponding to the variables are sorted from small to large, and then output in $1\%,5\%,...,99\%$ corresponds to the value of the variable — look at itIs the data distribution uniform
  

Qualitative data

// 得到出现的次数(Freq)
tabulate 变量

• This function only analyzes one variable at a time

tab 变量 ,gen(A)

• Generate dummy variables $A1...An$

• For example, in the figure, there are two recipes, there are two dummy variables $A1,$
  When$A$$2$ is the first formula,$A1==1;A2==0$
  When it is the second formula,$A1==0;A2==1$

Excel draws frequency fan chart of variables

1. Insert -> PivotTable
2. Select the desired field
   
   You can choose how the value is displayed (number or percentage)
3. Draw a fan chart
   analysis -> data perspective chart
   

• Add numbers to the picture
  

• In order to make the drawn pictures have a sense of beauty,
  you can sort them before you start drawing -> Sort
  Color can be changed: Page Layout -> Color

Visualize data-data bars