python方差检验是什么意思

import pandas as pd

import numpy as np

from statsmodels.formula.api import ols

from statsmodels.stats.anova import anova_lm

data = pd.DataFrame([[1, 1, 32],

                     [1, 2, 35],

                     [1, 3, 35.5],

                     [1, 4, 38.5],

                     [2, 1, 33.5],

                     [2, 2, 36.5],

                     [2, 3, 38],

                     [2, 4, 39.5],

                     [3, 1, 36],

                     [3, 2, 37.5],

                     [3, 3, 39.5],

                     [3, 4, 43]],

                    columns=['x1', 'x2', 'y'])

# 多因素无重复试验，不计算交互作用的影响

model = ols('y~C(x1) + C(x2)', data=data[['x1', 'x2', 'y']]).fit()

anovat = anova_lm(model)

anovat