t Tests for One Mean: Introduction

An introduction to t tests for one population mean. I briefly discuss when we use the test, and when we would use a z test instead. I also briefly discuss the hypotheses of the test, and the p-value for different alternatives. I then work through an example. (If you are comfortable with the basics of hypothesis testing, and understand the difference between t and z procedures from confidence intervals, then much of this video may be review.) If you are just looking for an example, it starts at 7:00.
The reaction time data is simulated data with the same summary statistics as found in:
Armstrong et al. (2012). Mild Dehydration Affects Mood in Healthy
Young Women. Journal of Nutrition, 142: 382-388.

[@LISA.WANG.]

Clear voice, good pace, simple and organized format, dark background easy on the eyes, great teaching with all the little details, it’s perfect- this is perfect, thank you very much.

[@jbstatistics]

Thanks for the very kind words!

[@PwNaSaUrUsxLEET]

SE(X)

[@rdenHotEd]

I'm such a child :(

[@RexGalilae]

2A All Day Hehuehuehue

[@abands5082]

69

[@manchao1416]

best tutorial series on statistics on youtube

[@fife8332]

I wish you'd continue to be enthusiastic in your videos like the earlier ones. Its so rare to find someone talking about statistics with actual enthusiasm in their voice. Its also rare that a person laughs when watching a video on two sample t-tests. But I think your videos are very concise and enlightening. Thanks for your work with these videos!

[@taihuang2033]

This series is awesome!

[@BrainNP]

Thank you so much! Very clear, easy to understand and it was fluid flowing! Thanks eh! :)

[@erikhallberg2248]

Thank you. This video is a wonderful help for learning t-tests

[@kayhankurul4113]

In next 3 hours, I will be examined for my class Statistical&Quality Control... I understood very clearly! :D

[@sarawilliams5826]

so helpful, I've enjoyed all of the jbstatistics videos. thank you!

[@ayahazzam7781]

amazing video!!! thank you so much

[@varshahushare6981]

Great explanation

[@Fabelot1]

Thanks for a great explanation! Don’t boxplots show the median where the thick line is, tho?

[@TylerCJF]

I am in an applied statistics and research class and I am currently reviewing for our upcoming final. I enjoyed the video. It was straight forward and informative. One thing that I would like to see and what I am still trying to figure out is when you should apply the one sample t-test rather than another test such as the two sample t-test or the matched pairs test or even simple linear regression. For my final I will just be given a word problem and I will have to decide which test to use on my own without being told. There are 7 different tests that the professor may ask us about so differentiating between each is where I struggle. Anyway good video and I'm just giving my feedback. Thanks for reading.

[@jbstatistics]

Thanks for the feedback. I've been pondering videos of that nature for some time, and will get to that sort of thing eventually.

[@omaromar-ot8ih]

How you can recognize between testing hypothesis and chi square if your doctor give a question, because both have the same information...?!

[@lensong8399]

When you explained the 3 situations whether uu0 or u=/u0, I don't understand why the u=/u0 is the double area of u or

[@Sim1991eon]

"Drawing conclusions about young woman in general is dubious at best" haha thats true even when you are not talking about stats.

[@adamhall7100]

When I run the command pt(1.389,24,.025,lower.tail=FALSE) in R I get .09280314, not .0888... What am I doing wrong?

[@katherinedavis2041]

What do I choose in my calculator when using software?

[@RA-ij7zx]

But if the t distribution has a large number of samples we can measure it as z ,as my teacher said.

[@kartaLaLa]

why divided by standard error ?

[@dellaameliaa27]

how do i know which one to use, t table or normal distribution or F table?

[@jbstatistics]

If we needed to find an area or percentile of a t distribution (which would arise if we were doing a t test without using software), then we'd use a t table. If we needed to find an area or percentile of the standard normal distribution (which would arise if we were doing a Z test without software), then we'd use a standard normal table. If we needed to find an area or percentile of an F distribution (which would arise if we were doing an F test without software), then we'd use an F table..

[@richardl.4374]

In 12:10 if we were to use the critical value from the t table it would be 2.06 and since the value we got was 1.389 we fail to reject the Null hypothesis correct ?

[@richardl.4374]

While if a=0.05 but it alternative hypothesis is one sided , saying mu > mu not , the critical value would be 1.711? And since 1.389 would still not be within 1.711 we again fail to reject the null hypothesis in this case ?

[@devendrapratap9608]

@@richardl.4374 same confusion

[@donnasmith8529]

Excellent videos. I teach statistics at the community college level. I have a Masters in Mathematics not in statistics. I notice you use the term zed for z, am I incorrect in saying z rather than zed? I am assuming zed is the Greek equivalent to z.

[@faalentijn]

So, I am about to fail statistics but I am pretty sure this more a dialect thing than anything else. In American English it is common to pronounce the letter z as zee, while in British accents they prefer pronouncing it as zed. Jeremy Balka is a professor at a university in Canada where they use British English so he pronounces it as 'zed'. In short, they way you were teaching your students is fine :)

[@JiangXiang]

Although Canada do not speak British English, they do use 'zed' for z :)

[@stefanfarier7384]

All this time.... I was wondering "what exactly is a t-test"? And I've been doing it for years

[@goobydoo9278]

1:45 hehe, SE(X)

[@mmaking8664]

how did you get 1.389?

[@aryamotegaonkar7978]

let the null hypothesis be that the given t-distribution has the required degrees of freedom......

[@EvilSapphireR]

Aaaaand we never got the video for the two samples T test.

[@jbstatistics]

I have extensive video coverage of the two-sample t test.

[@EvilSapphireR]

@@jbstatistics Haha I didn't realise you still are replying to these videos. I've been following your entire sampling series for the last few days just for the fun of it, and you make the subject so intuitive! Kudos!

[@jbstatistics]

@@EvilSapphireR I'm lucky enough to still be alive and still teaching stats, and I still pop in every now and then to comment. Thanks for the kind words!

[@spectator5144]

i love you

[@thecanadianpig5415]

haha SE(X) funny

[@savageanimal8420]

can you be me stats teacher ?

[@deadbunnyeyes190]

SE(X)