残差分析（含直方图）

def solve():
    import pandas as pd
    import statsmodels.api as sm
    import matplotlib.pyplot as plt
    
    df = pd.read_csv('https://liangdaima.com/static/data/wooldridge/wage1.csv')
    X = sm.add_constant(df[['educ', 'exper', 'tenure']])
    model = sm.OLS(df['wage'], X).fit()
    
    plt.figure(figsize=(10,6))
    plt.hist(model.resid, bins=20, color='steelblue', edgecolor='black', alpha=0.7)
    plt.title('残差分布直方图', fontsize=14)
    plt.xlabel('残差', fontsize=12)
    plt.ylabel('频数', fontsize=12)
    plt.grid(axis='y', alpha=0.3)
    plt.tight_layout()
    plt.show()
    
    print(f'{model.resid.std():.4f}')