from scipy import stats
import matplotlib.pyplot as plt
import seaborn as sns
lunch = df[df['time'] == 'Lunch']['tip']
dinner = df[df['time'] == 'Dinner']['tip']
stats.ttest_ind(lunch, dinner, equal_var=False) # Welch’s
t_stat, p_t = stats.ttest_ind(grupo_A, grupo_B)