Z scores explained statistics

[elight07]

Thanks!

[bieberhaterz280]

fuck u

[ramgon254]

Thank you so much for your time here. You did an excellent job of explaining the foundation so the rest can be more easily understood. Can you teach my stats prof (who is a rocket scientist) how to teach this stuff? Thanks again!!!!

[MsEmm22]

these percentages are given?

[bas75252]

Very well explained and I appreciate the clear illustrations/visuals

[bas75252]

Very well explained and I appreciate the clear illustrations/visuals

[cool08player]

i think i realized the equation for z score. z score= standard deviation divided by the mean of scores. if the standard deviation is higher than the mean, then ur z score will be positive. if the standard deviation is lower than the mean, then ur z score will be negative.

try it :)

[statisticsfun]

@cool08player by george I think you have it!!!

[cool08player]

@statisticsfun lol you really think so?

[Turtlebear]

Thumbs up if You're from Ryerson!

[ongolos]

why do all ur vids have the right speaker speaking only, can u get a better audio mic or recorder? hurts my ears cuz the audio is so bad.

[statisticsfun]

@ongolos when I first started doing these vids I used an standard simple microphone. Now I use a nice microphone two channels (left and right) and all my videos are in high definition too. I a plan on redoing all the old videos.

[ongolos]

@statisticsfun thats good , i hope its going to be better, I real think these vids are helpful but cant concentrate with all the noise the mic captures. I got EAX so it captures a lot out of the sound... its like anti BASS. Lookin forward to the new ones!

[baker70romeo]

ok.. i have the Z score, now what's the formula to figure out the area.

[statisticsfun]

@baker70romeo you look up the z score in the body of the "normalized table" in the back of your stats book. Watch the video I attached above called, "Normalized z score question for statistics" -- also I have a playlist called z scores.

[SteevanNas]

I CANT HEAR>

[statisticsfun]

@SteevanNas sorry you can't hear. I have put all the z score videos in a place list on my channel statisticsfun called z scores.

[stringcatt]

i HAVE A ? IF 5% OF BABIES CAN WALK BY 10 MONTHS AND 75% BY 13 MONTHS, WHAT'S THE SD AND MEAN? I DON'T GET IT. ANS: MEAN =12.1 SD= 1.3.

[statisticsfun]

@stringcatt there is a good reason this is confusing you... because it is a really really hard problem. I am creating a video response and I should have it posted this morning for you.

[statisticsfun]

@stringcatt I just posted an explanation video "Normalized z score question for statistics" You will see it as a video response.

[raizadateaching]

Great video tutorial! You might be interested in some interactive demos on basic stats which I made in Python and Matlab. They allow the user to play around with adding data points, in order to get an intuitive feel for how the Normal distribution, t-tests and correlation behave. A video showing the demos in action is in my YouTube channel.

[stringcatt]

isn't the z score for 1.96=.9750?

[StarryEchoes]

thanks, very helpful.

[jillymwaxx]

i actually got it! finally

[wopperjr]

how did you get the 47.5 percent at 2:00 minute mark??

[holyorderoftruth]

@wopperjr In most z score distributions, an alpha level of 5% across two-tails is used as the critical point for rejecting the null hypothesis. That said, 47.5% leaves you 2.5% on each tail, which adds up to the 5%. Furthermore, if your score is in this 2.5% or a z score of more/less than +- 1.96, t is significant.

[stringcatt]

@holyorderoftruth isn't the z score for 1.96=.9750?

[statisticsfun]

@stringcatt Well... good question (and I need to make a video on this) The .9750 is the total area below 1.96. In the video I talk about the area between the mean and 1.96 which is .4750 (47.5%).

Summary

Total Area below 1.96 = .9750

Area below the mean (where z =0) = .5000

Area between 1.96 and the mean is .9750 - .5000 = .4750

[stringcatt]

@statisticsfun So the .9750 includes the "yellow tail " to the left of +1.96 but not to the right of 1.96. .9750 + .0250= 100%? Thanks

[statisticsfun]

@stringcatt Yes you would be correct. This is confusing because the "normalized" tables at the back of stats books are not exactly the same. This seems to be a common problem and I need to do a video on this topic too.

[YeaItWasOkay]

really well explained, thanks

[muzic29]

how do you calculate the area under a normal curve when the z score is high? (for example -6)?

[jedcee17]

the audio seems concentrated to the left ear...

yet the presentation is great!

what application did you use to make this?

I just wanna learn it...

thanks!

[gnuochtapir]

How high/low can a Z score be? How many standard deviations can there be in each direction?

[statisticsfun]

@gnuochtapir The Z score has no upper limit.... Z scores more than 3 are uncommon and so is anything more than 3 standard deviations way too. A z score of 4 is way out there and a z score of 5 is off the charts.

[gnuochtapir]

@statisticsfun ok, thanks!

[d3mur3]

@statisticsfun okay so i was computing a z-score and it turns out to be 4.19 how do i find the p-value?

[statisticsfun]

@d3mur3 it turns out to be really small. The p value is the area to the right of the z score (if z score is positive) and to the left (if z score is negative). The p value for a z score of 1.96 is .025. If the z score is 2.9, then the p value is .0019.

I know this is frustrating, but there is a bit more -- in the normal table if you look up 1.96 you will see a value of .4750. (1 - .4750) = .025.  The same is true if you look up 2.9. You will see the value of .4981 (1-.4981 = .0019).

[d3mur3]

@statisticsfun okay thank you :D and yes, this is really frustrating haha

[J4archae]

Wow man ! you made it so simple. My Stat teacher spend an hour on it and he sucks..

[WeaselHalfbreed]

@J4archae All stats teacher suck!

[TAC5Patriot]

Thank you for your video. Very informative.

[inuspike1]

I quite literally got more from this than an entire semester of statistics 112. many thanks

[darrinpatterson]

The .34 is not accurate. The z-score associated with 1 is .1587. It needs to be explained how you came to this arbitrary value.

[statisticsfun]

@darrinpatterson The .34 is the area from the mean to one standard deviation away from the mean (z score = 1). The .1587 is the area to right of this. Note that .34 + .157 is just about .5000 which is the area to the right of the mean. You should be able to find these values in a table in the back of any stats book. "proportions of area under the standard normal curve."

[vazir98]

the explanation is simple and clear to understand.

[ruellan2003]

excellent video ...thank you

[muffemod]

Z scores are the number of standard deviations away from the mean.

[MistuhPurpo]

Oh come on Gisela.

[sullivanseven]

You are glowing like a pearl under the blanket

[rn1414]

Outstanding video--thank you!

[Nanumir]

"is __ z-scores", I think that sounds a bit silly, shouldn't it be "are __ z-scores" great video though thankkkz

[cyz872]

i sort of btr unstd what's Z table all about now. cheers (:

[Talian1]

Great job of explaining.. Thank you.

[trueshinobi01]

Great job! I've learned more after watching this!

[shibamatachick]

Excellent. Thank you.

[scottydangles14]

thanks for posting this. I understand now.

[bolletrie]

This was a good video. explains it perfectly0

[lavedon]

This is a fantastic service, perfectly executed thank you!

[truthimportant]

Thank you much! you are making up for my professor who has trouble communicating concepts!

[nonameisavailable]

I love how you made use of visual media. The numbers were floating to the right places, the arrows were moving symmetrically. This is the way math should be taught; and you are an excellent brilliant man. I am sending out a lot of blessings to you!

[masandra123]

I Love it!! Thank you!!!

[Think40]

that's what I'm talking about. Thanks

[johnny99james]

thank you for posting this, it really does help.

[shogunkata]

great stuff. thanks for posting

[seidolce]

I used Keynote. I create everything on a Mac. Keynote is part of iWork.

[foxgirl100]

Thank u very much, this is just right. Did u use powerpoint to create this?

[mateilly]

Move a little faster. otherwise greate

[mttellek]

Also well done - what are you using to make these videos..? Make some more, please.

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