The Sampling Distribution of the Difference in Sample Means (X_1 bar - X_2 bar)

I discuss the characteristics of the sampling distribution of the difference in sample means (X_1 bar - X_2 bar). I then work through an example of a probability calculation that involves these concepts.

The values for male and female heights are based on information in the 2009-2011 Canadian Health Measures Survey.

[shannarudovclark]

I'm new to teaching statistics and I find your videos to be a valuable supplement to the text book because you explain the reasoning behind the equations that are usually just given in 'rule book' style. thank you!

[tomroth]

Thanks for the clear explanation. Love your videos by the way, best ones on the internet I've found so far.

[Adam-gpij]

I would like to say thank you so much ! I really learnt a lot from you and you are the best teacher ever !we really appreciate that efforts

[jbstatistics]

At 5:56 I'm discussing the sampling distribution *of the sample mean*, which has a variance of sigma^2/n. At 5:02 I'm discussing the distribution of heights (which is the distribution of the height for a single person, not the distribution of the mean height of n people), and the variance of this distribution is sigma^2.

I discuss why the variance of the sample mean is sigma^2/n when the sampling distribution is first brought up (in my "sampling distributions" playlist).

[farahariyanti]

THANK YOU FOR THE CLEAR EXPLANATION, EASY TO UNDERSTAND

[jbstatistics]

You're welcome, and thanks very much for the compliment!

[yt-]

you have some great stuff. not only the content also the presentation and I also like that the background is black. I can watch hours long on my phone without draining much battery.

[貓耳亨]

In the last problem (since 7:00), is the different number of 20 males amd 15 females taken account. If so, how? If not, why? Cheers

[hayaansari]

Look at 3:40 r u sure there will be + sign between var x1 bar and var x2 bar?

[jacob]

Way more concise than khan academy. Thanks

[MaudinaRohmah-oi]

can u more explain about how the results of variance is positive not negative i know is came from -1^2 but just clear it can you explain again?

[BhartLal-cdxc]

in the second part of the qstn, arent we supposed to work with mu 1 and mu 2 and not x bar 1 and x bar 2?

[nazdash]

Thanks a lot for video. Very clean and useful.
What will change if I need to calculate the difference between two weighted means?

[tomroth]

At 5:56, why do you divide the variance by the sample size? (in X_m ~ N(177.7, 5.6/20). Why is this not done at 5:02?

[richashrivastava]

Why are variance added and not substracted?

[someshagl]

Thanks for the videos. They are really awesome. I have a small question in this video, At 8:20, we subtract the mean (14.7) which was anyway equal to X bar m - X bar F. Doesn't this make the numerator within P zero? I did not get this part

[Jdonovanford]

Is that also called the standard error? (for the sampling distribution of the sample mean)

[sahiraazhar]

what if the question is between 3.4 &5.9? is it still the same we do like normal dist?

[yashnagda]

Previously it was
Z = x bar - u0 / sigma/sqrt(n)

But here x bar and u0 is reverse ehy is that.