i know this was 9 years ago but i just wanted to let you know i just passed my math final in college because of your channel. Appreciate the simplicity.
Your flowchart alone has taught me more in 30 seconds than I've learned in the last 30 days of this term. I truly believe videos like yours represent the future of education. Suffice to say, THANK YOU for making this video! And yes, like others have commented, your voice is a nice touch!
You're out here saving lives! I'm taking a fully online course with zero instruction and got about a 30 percent on our quiz that mostly focused on this topic. I was so confused and you've helped me feel 100% ready to conquer this on the final. THANK YOU!!
I have a huge Stats test in 2 two days...and you have saved me from academic obliteration. You made things so thorough. You very well may have saved me from flunking out and having to sell drugs to survive. Now I should be able to graduate and help mankind just as you have. Thank you so much :-)
You saved my but for a stat test! I was freaking out, not getting the right answers at all, and your clear, concise video calmed me down enough to realize that my answer key was FOR THE WRONG PAGE! The universe makes sense once again!
Ty! Confidence intervals by hand was making me cry, especially since our professor said to use the ti 84 for 99% of our work. My class is online and my professor is great, but I'm sitting here at 12 midnight and not able to ask him. So ty very much for making this so simple.
Your videos are amazing! After trying to understand the entire section of the book and a near three hour lecture, you have summed it up in less than 15 minutes. Excellent! Thank you!
Thank you so much for uploading this! I have been struggling with stats since I started, and having this portion simplified so much is awesome. Thanks again!
It's actually a program that allows me to do it. It's called the TI-84 Smartview Emulator. It costs about as much as the calculator, but you can probably find a free trial.
TY very much for your awesome math videos. They have helped a lot with me learning how to use my TI-84Plus calculator. I do have one question-How do you get the calculator keys to appear on the side of the screen? Is it a font that can go into Microsoft Word? My teacher is requiring that we list what keys we pressed on our calculator to get to our answer and if there is a font or clip art I can add to the word document I use to turn in my work it would save me a huge amount of typing.
Hi Ashley, I think there may be an error in your flowchart. We need to confirm that we have over 30 values or know that the population is Normally distributed to use either ZInterval or TInterval. After that confirmation, we check to see if we are given the Population Standard Deviation to decide on which TI app to use.
Is there a reason why my answers are coming out slightly off of the correct answers. I am inputting everything correctly. I am wondering if there is a setting that needs to be changed.
All of this is great. it is far better than someone saying ''use technology'' and nothing else. not everyone knows HOW to use the technology. I have learned FAR MORE HERE than with the ''use technology'' person. Now this is weird but for the last example of the shoes, I did it 5 times because i get a different end result then here, and i rechecked my L-1 20 times. but I am ok with it, the method is what counts, yes I know I need to match the correct numbers, but I KNOW HOW TO DO IT NOW. Most of my results match but the 2 'big' numbers are slightly off, i will re do them again. T.Y.
This has been the best tutoring video I have seen as of yet, and I've seen probably 50 by now! Thank you so much for posting this! I finally understand when to use each function, that was killing me.
Thank you very much. That video was a big help to me. Are there any other things we should know about this? My professor goes so fast, hes from India, and when someone gets stuck all he tells them is life is very fast paced in the US and you have to keep up!. He should go back to India, and stay there.
for the example with the t-interval, how did you know it was s and not sigma? It appears to be worded the exact same as ex 1 but you got s and not sigma.
It is assumed that the question gives the population standard deviation, thus she did not mean what you are sure of. That's why in the video Dr. Ashley uses the Z-interval. A Z-interval is used when population standard deviation is known, whereas if the population standard deviation is not known then a T-interval must be used.
Isn't sigma (Standard deviation)? It's known on both.. so why are we treating the second problem as if we don't know the value of sigma for the second one?
Good question. In that case, you need to use what are called "non-parametric methods." That is not usually covered in an introductory statistics course. You simply need to explain that it cannot be done using the techniques available.
How can I solve this problem in the TI-83? A researcher scholar wants to know how many times per hour a certain strand of viruses reproduces. The mean is 11.4 per hour with a variance of 3.24. How large of a sample would be required in order to estimate the mean number of reproductions per hour at the 90% confidence level with an error of at most .16 reproductions.
Mathos1 I responded to the email you sent me, but I figured I would respond here in case you see this first or someone else has the same question. Sigma is the population standard deviation, so we know that in the first problem. In the second problem, we do not know the population standard deviation, we only know the sample standard deviation, s.
Some of my videos are done with a tablet PC, so I can write directly on the screen. Other's are done (and I think this is one of them) with a bamboo tablet.
How would I figure out the mean, if the mean is not provided? Here's the question: A doctor wants to estimate the mean HDL cholesterol of all 20-to-29 year-old females. How many subjects are needed to estimate the mean HDL cholesterol within 4 points with 99% confidence assuming sigma=14.3? Suppose the doctor would be content with 95% confidence. How does the decrease in confidence affected the sample size required?
NO, it is correct and every Elementary Statistic book states this (I have 10 of them and they all confirm). If its normally distributed, and sample size is greater than 30, you can use the sample standard deviation to find the point estimate.
Great videos! To offer a differing experience: I teach business statistics and our online homework platform will count an answer wrong if a student uses z rather than t, regardless of sample size (so students should probably check what their book and prof are expecting). After looking through a few business statistics textbooks, I found: (1) Bowerman, O'Connell, Murphree state it's ok to use z when n > 100; (2) Doane & Seward, and (3) Groebner, Shannon & Fry, advise using t regardless of n. Interesting.
@@quantquill In most Math Stat class, for n greater or equal to 30, when the population standard deviation sigma is unknown, you can just substitute the sample standard deviation s for sigma. I don't know where you teach? Some community college?
Hi, @@kelvinella , we're talking about whether to use the Z interval or the T interval in the calculator, given a large sample size. Yes, we substitute the sample standard deviation when we don't know population standard deviation. AGodboldMath has textbooks which state that when n > 30, it's okay to use the Z Interval, because s is expected to be close enough to sigma. My textbooks state this is okay when n > 100, or (in 2 of the books) we must always use the t distribution, regardless of sample size. Here's an illustration of the difference in final answers: Construct a 95% confidence interval for xbar = 80, s = 12, n = 100. If you use Z Interval, it's (77.648, 82.352) and with T Interval it's (77.619, 82.381). Students should consult their textbook or professor to see what is expected.
