使用python查找置信区间

Question

I am trying to calculate confidence interval using margin of error but it is giving me an error. Below is the code I've written. Please help!

import pandas as pd
import scipy.stats as stats
import math
import numpy as np
import warnings

warnings.filterwarnings('ignore')

sample_size=2000
z_critical = stats.norm.ppf(q = 0.95)  

# path        [File location variable]
#Code starts here
data = pd.read_csv(path)
data_sample = data.sample(n=2000, random_state=0)
sample_mean = data_sample['installment'].mean
sample_std = data_sample['installment'].std()
a = sample_size ** 0.5
margin_of_error = z_critical * (sample_std/44.721)
confidence_interval = (sample_mean + margin_of_error, sample_mean - margin_of_error)

which gives:

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-1-3f5eda42a1b0> in <module>()
     24 # print(type(a))
     25 margin_of_error = z_critical * (sample_std/a)
---> 26 confidence_interval = (sample_mean + margin_of_error, sample_mean - margin_of_error)
     27 true_mean = data['installment'].mean
     28 print(confidence_interval)
TypeError: unsupported operand type(s) for +: 'method' and 'float'

Answer 1

Most probably, this is due to a typo - you are missing parentheses in

sample_mean = data_sample['installment'].mean

it should be

sample_mean = data_sample['installment'].mean()

mean (no parentheses) is a method and not a float, hence the error when trying to add it to margin_of_error (which is indeed a float).