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Understanding the p-value

Please view new version: http://www.youtube.com/watch?v=eyknGvncKLw
by CreativeHeuristics. Now part of an app: AtMyPace: Statistics.

Uploaded by: UCMSCI
Tags for this video: statistics p-value probability mello phoenix wright production canterbury comedy tutorial near mean hypothesis test

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Array ( 1 year ago by UCMSCI)

@babish82
Well done. What you say is correct in essence, though a bit dodgy in terminology (even by my standards). You've got it. Just remember the probability is of getting that result, even though we act as if it is the probability that the alternative hypothesis is true.

@UCMSCI Thanks a ... ( 1 year ago by babish82)

@UCMSCI Thanks a lot...actually, I'm a man of medicine, and statistice is a completely new thing for me, thus I had to put in a lot of thought in it, in my own way...but thanks a lot...you're an angel...

0.2578 is the p- ... ( 1 year ago by mysteryg)

0.2578 is the p-value I got when I manually tried to calculate this. I used the sample deviation and looked at the Z table, I thought of looking at the t-table but I wouldnt know about that because I dont have an alpha.

@mmmcr00 get the ... ( 11 months ago by puttjattda101)

@mmmcr00 get the casio fx-9750 gii and ull be set

I hate finals. ... ( 11 months ago by JoeDaPlumber)

I hate finals. This vid helps a lot.

Array ( 10 months ago by Yngwiaever)

Helen?
That's a guy.

Are you a Kiwi? ... ( 10 months ago by KRKbert)

Are you a Kiwi? Sounds like it!

Feenie Wright in ... ( 10 months ago by PhoenixWright1000)

Feenie Wright in this vis makes it 10x more awesome.

@KRKbert Yus. ( 8 months ago by UCMSCI)

@KRKbert Yus.

Death note! ( 7 months ago by TradingTutor)

Death note!

The p value seems ... ( 7 months ago by palui)

The p value seems to be calculating a probability AFTER the data is in. In other words, it's producing a probability after the random event concludes. But after the data is in, there is no probability anymore. It seems the probability that I received my data, or something more extreme, after the data has been received, is 1. Seems odd.

But how do you work ... ( 6 months ago by efb420)

But how do you work out the p-value?

@efb420 If you look ... ( 6 months ago by UCMSCI)

@efb420 If you look at my response to @mmmcr00 above, you can see how. Generally the computer package works it out, and we interpret it.

youtubing stats ... ( 3 months ago by LastDodosaur)

youtubing stats stuff while trying to cram for test. See pheonix wright in thumbnail. ... ... ... It's 3 AM.

@palui The P-Value ... ( 3 months ago by IceAges14Aces)

@palui The P-Value is technically the probability of extreme or more exteme of getting an observation like the one actually observed in your study/experiment when the null-hypothesis is true. For instance, suppose I ran 20 studies and our alpha level is 0.05 level. What does this mean? It means that if you run the study 20 times you would get a statistically significant result at the P=0.05 significance level only by pure luck.........
P=0.05 means 1 in 20.

@IceAges14Aces I ... ( 3 months ago by palui)

@IceAges14Aces I had figured out my error after I had made my comment. Thanks for your reply. However, your reply isn't worded correctly. The p value can be described as: In all possible random repeated samples of size n from a population for which the null were true, the proportion of times for which your test statistic was as large or larger than the value realized in your observed data is the p-value. p=0.05 has nothing to do with running a study 20 times.

@palui I was giving ... ( 3 months ago by IceAges14Aces)

@palui I was giving you an example of what P=0.05 means, not that P=0.05 is always 20 studies.
You're definition of the P-Value is correct by the way.......

I wish all my ... ( 3 months ago by DaisyExodus)

I wish all my lectures were like this...

@DaisyExodus Thanks ... ( 3 months ago by UCMSCI)

@DaisyExodus Thanks. We are busy remaking some of these so we aren't breaking copyright (!) And making some more. We are also putting them into an iPad app, along with intereactive quizzes to help people learn. SO thanks for the encouragement. We really appreciate it.
The new videos will be at CreativeHeuristics Youtube channel, and the app will by AtMyPace:Statistics. Tell your friends.

@vinzbrain to be ... ( 3 months ago by yzy010858)

@vinzbrain to be precise alpha>=0.05

Array ( 3 months ago by vinzbrain)

@yzy010858
isn't it that you fix alpha to whatever value you want and then test p against your alpha?
If that is true then I am not sure if you are being very precise

@vinzbrain I'm ... ( 2 months ago by UCMSCI)

@vinzbrain I'm afraid statistics is far from precise. In fact the choice of alpha is a remnant from when p-values were difficult to calculate. Really we look at the size of the p-value and judge from that.

"p is low, null ... ( 2 weeks ago by flukemate)

"p is low, null must go" <-- love it