What is Two-sample T-test? Easy Explanation for Data Science Interviews

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The t-test is one of the most basic, and commonly used hypothesis tests. There are many data science interview questions on t-tests, so in this video, we’ll dive into how to conduct two-sample t-tests.
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====================
Contents of this video:
====================
0:00 Intro
0:51 Independent samples
2:22 Two-sample t-test with equal variances
4:06 Welch's t-test with unequal variances
2:24 Difference between the t-distribution and the normal distribution
8:43 Dependent samples

Опубликовано:

3 авг 2024

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Комментарии : 11

@emma_ding Год назад

Many of you have asked me to share my presentation notes, and now… I have them for you! Download all the PDFs of my Notion pages at www.emmading.com/get-all-my-free-resources. Enjoy!

@abhisek-chatterjee Год назад

One small thing Emma. The test statistic T follows t(n1+n2-2) i.e. a t-distribution with degrees of freedom n1+n2-2, not t(n1+n2-2,alpha/2). The former is the distribution of T, the latter is the threshold value of it corresponding to significance level alpha for a both-sided test. It's a small thing, but beginners may confuse, that's why I said.

@alanpdrv Год назад

Hi Emma. Would you ever make a video on doing A/B/C tests? (or A/B/C/n tests). I recently proposed one during a job interview and have been thinking through the implications of it. Maybe you could talk about multi-treatment effects, the multiple comparisons problem, using a bayesian framework to deal with some of the pitfalls, and maybe comment on why some DSs stay very clear of doing these kind of tests whereas others will very happily embrace them?

@AllieZhao Год назад

Very clear, I like the way using notion to demonstrate your knowledge.

@emma_ding Год назад

Thanks, Allie! I'm so glad to hear you're finding it helpful.

@Philgob Год назад

very nice

@jessicagrant6830 10 месяцев назад

Hey Emma, something is incorrect in either your test statistic or confidence intervals reported as with the test statistic you conclude to reject the null but the confidence interval would concludes that you fail to reject the null because the test statistic falls within the bounds. These should always provide the same conclusion, can you explain what caused the inconsistency? Thanks!

@austinhoag5130 7 месяцев назад

What's the intuition behind the degrees of freedom for the unequal variances scenario? That seems like a hard equation to remember during an interview.

@star_7776 Год назад

In 2:24 should not be : If t-statistic < t-critical value, reject H_{0} ? Or I am confused

@user-kv3hu6qe6z Год назад

Hey emma , Since you were coding in python , why didn't you use the scipy library "ttest_ind" method to calculate the welch t-test and just set the variance parameter to FALSE . is it that this straight forward approach is not allowed in interviews . I am new to statistics , so genuinely asking because i do no not know . THAK YOU and great videos