样本量与标准误关系图

def solve():
    import pandas as pd
    import numpy as np
    import matplotlib.pyplot as plt
    url = 'https://data.zuihe.com/wooldridge/wage1.csv'
    df = pd.read_csv(url)
    sig = df['wage'].std(ddof=0)
    ns = [10,20,50,100,200,500]
    ses = [round(sig/np.sqrt(n),4) for n in ns]
    for n,se in zip(ns,ses): print(f'n={n}: SE={se}')
    plt.plot(ns, ses, 'o-', color='steelblue')
    plt.xlabel('n'); plt.ylabel('SE'); plt.title('n与SE关系')
    plt.tight_layout(); plt.show()