Table 1 The descriptive statistics of variables.

 Output

Total output value of grain crops (yuan)

13291.11

25863.23

 Labor input

The number of laborers engaged in agricultural production for more than 3 months in a year (person)

1.693

0.703

 Land input

The planting area of grain crops (mu)

9.943

21.536

 Capital input

Amount of direct investment in grain planting, including expenditure on cultivation, fertilizers, pesticides, etc. (yuan)

5284.292

11429.85

 Age

The age of the head of the household

55.213

10.919

 Gender

1 if the head of the household is male, 0 otherwise

0.916

0.277

 Education level

The education level of the head of the household: 1 = not attending school; 2 = primary school; 3 = junior high school; 4 = high school or secondary school; 5 = college or above

2.468

0.839

 Ethnicity

1 if the ethnicity of the head of the household is Han nationality; 0 otherwise

0.899

0.302

 Health status

The health status of the head of the household: 1 = very unhealthy; 2 = less healthy; 3 = general health; 4 = relatively healthy; 5 = very healthy

3.477

1.035

 Household size

The total number of household members

4.419

2.107

 Total household income

The total income of the household (yuan), treated as a logarithm

9.736

1.159

 Village topography

The terrain of the village: 1 if the terrain of the village is plain; 0 otherwise

0.566

0.496

 Village size

The number of households in the village

6.290

0.749

 Distance to county

The distance between the village and the county (km)

24.204

22.598