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Learn Performing a t-test in Python | Statistical Testing
Learning Statistics with Python

bookPerforming a t-test in Python

To conduct a t-test in Python, all you have to do is specify the alternative hypothesis and indicate whether variances are roughly equal (homogeneous).

The ttest_ind() function within scipy.stats handles the rest. Below is the syntax:

st.ttest_ind(a, b, equal_var=True, alternative='two-sided')

Parameters:

  • a β€” the first sample;
  • b β€” the second sample;
  • equal_var β€” set to True if variances are approximately equal, and False if they are not;
  • alternative β€” the type of alternative hypothesis:
    • 'two-sided' β€” indicates that the means are not equal;
    • 'less' β€” implies that the first mean is less than the second;
    • 'greater' β€” implies that the first mean is greater than the second.

Return values:

  • statistic β€” the value of the t statistic;
  • pvalue β€” the p-value.

The focus is on the p-value. If the p-value is lower than Ξ± (usually 0.05), the t statistic falls within the critical region, leading to the acceptance of the alternative hypothesis. If the p-value is greater than Ξ±, the null hypothesis is accepted, indicating that the means are equal.

Here is an example of applying the t-test to the heights dataset:

123456789101112131415
import pandas as pd import scipy.stats as st # Load the data male = pd.read_csv('https://codefinity-content-media.s3.eu-west-1.amazonaws.com/a849660e-ddfa-4033-80a6-94a1b7772e23/Testing2.0/male.csv').squeeze() female = pd.read_csv('https://codefinity-content-media.s3.eu-west-1.amazonaws.com/a849660e-ddfa-4033-80a6-94a1b7772e23/Testing2.0/female.csv').squeeze() # Apply t-test t_stat, pvalue = st.ttest_ind(male, female, equal_var=True, alternative="greater") if pvalue > 0.05: # Check if we should support or not the null hypothesis if pvalue > 0.05: print("We support the null hypothesis, the mean values are equal") else: print("We reject the null hypothesis, males are taller")
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SectionΒ 6. ChapterΒ 6

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bookPerforming a t-test in Python

Swipe to show menu

To conduct a t-test in Python, all you have to do is specify the alternative hypothesis and indicate whether variances are roughly equal (homogeneous).

The ttest_ind() function within scipy.stats handles the rest. Below is the syntax:

st.ttest_ind(a, b, equal_var=True, alternative='two-sided')

Parameters:

  • a β€” the first sample;
  • b β€” the second sample;
  • equal_var β€” set to True if variances are approximately equal, and False if they are not;
  • alternative β€” the type of alternative hypothesis:
    • 'two-sided' β€” indicates that the means are not equal;
    • 'less' β€” implies that the first mean is less than the second;
    • 'greater' β€” implies that the first mean is greater than the second.

Return values:

  • statistic β€” the value of the t statistic;
  • pvalue β€” the p-value.

The focus is on the p-value. If the p-value is lower than Ξ± (usually 0.05), the t statistic falls within the critical region, leading to the acceptance of the alternative hypothesis. If the p-value is greater than Ξ±, the null hypothesis is accepted, indicating that the means are equal.

Here is an example of applying the t-test to the heights dataset:

123456789101112131415
import pandas as pd import scipy.stats as st # Load the data male = pd.read_csv('https://codefinity-content-media.s3.eu-west-1.amazonaws.com/a849660e-ddfa-4033-80a6-94a1b7772e23/Testing2.0/male.csv').squeeze() female = pd.read_csv('https://codefinity-content-media.s3.eu-west-1.amazonaws.com/a849660e-ddfa-4033-80a6-94a1b7772e23/Testing2.0/female.csv').squeeze() # Apply t-test t_stat, pvalue = st.ttest_ind(male, female, equal_var=True, alternative="greater") if pvalue > 0.05: # Check if we should support or not the null hypothesis if pvalue > 0.05: print("We support the null hypothesis, the mean values are equal") else: print("We reject the null hypothesis, males are taller")
copy
Everything was clear?

How can we improve it?

Thanks for your feedback!

SectionΒ 6. ChapterΒ 6
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