Ok, I got the numbers confused, my bad. Looks like I've been mixing up two formulas with the ones you've provided me and the ones I have in my lecture notes.
In my post #10 I have put the numbers into a spreadsheet to calculate it so there shouldn't be any errors, not even decimals.
Question...
Looking at the sum of the coated and uncoated pipes, or the average, it looks to be the most likely result yes.
My calculations should get a confidence interval where both sums are greater than 0, but I've looked over this several times now and everything seem to be correct according to my...
I was looking through my formulas and numbers looking for a value##µ_X - µ_Y = ?##
I also thought the value that should be within the confidence interval should be +7.1 or -7.1.
Would the conclusion " ##Δµ = 0## is within the confidence interval, we can therefore not conclude that the treated...
There is, or there was. I took the answers I got from this thread and used with the formulas and notes I have and got this:
I have used different symbols. Want to find: ##Δµ = µ_X - µ_Y ## based on ##Δ_{\bar X \bar Y} = \bar X - \bar Y = 47.5 - 54.6 = -7.1##
Variance: ## \frac {(n_X -1)S_X^2 +...
## \bar X ## and ## \bar Y ## are correct since they are simply ∑##X_i## and ∑##Y_i## which are gathered from the exercise text, divided by 20.
Is ##S_X^2 = 64.158## and ##S_Y^2 = 132.253## the wrong numbers? I've double and triple checked those numbers. Repeating my formula:
##S_X^2 = \frac...
As andrewkirk suggested above, I used the formula in the link you both gave me, the formula after "test statistic". I just renamed it using Sx2 and Sy2 for it to be identical with the text in my exercise, instead of S12 and S22 as is used in the formula.
Hope this clears it up. Is it still...
I used this formula: ##T = \frac {\bar X - \bar Y}{\sqrt{\frac {S_X^2}{N_X}} + \sqrt{\frac {S_Y^2}{N_Y}}} ##
Where
##\bar X = 47.5##
##\bar Y = 54.6##
##N_X = 20##
##N_Y = 20##
And ##S_X^2## is calculated using normal sample variance:
##S_X^2 = \frac {(39-47.5)^2 + ... + (62-47.5)^2} {19} =...
I'm sorry, I must've typed the wrong formula when looking at the latex codes at the same time, I did indeed post the wrong formula.
But your reply here cleared up my confusion regardless, I will get back to you once I've completed this step if necessary.
Thank you for your reply. In the link you sent, I do not understand how to use the information to get a formula I can use to determine different variance for the two samples.
The formula $$T = \frac {\bar Y_1 - \bar Y_2} {S_2 \sqrt{\frac 1 N_1 + \frac 1 N_2}},$$ I feel like I have T and ##S_p##...
Homework Statement
The following two samples are corrosion values for 20 untreated pipes (Xi) and 20 surface treated pipes (Yi)
∑Xi = 950, ∑Xi2 = 46344 and ∑Yi = 1092, ∑Yi2 = 62136
We want to examine if there is basis to claim that the surface treatment reduce corrosion.
a)
1: Find a 95%...
I apologize! I had some addons, popups or Java settings blocked so I couldn't see the slides.
I'm now halfway through one of them, and I just got to the study cycle. I've been taking notes, and I just want to say this for everyone looking to improve their structure, effectiveness or the amount...
The site looks very interesting indeed, but does it require any log ins or purchase to get the full content?
It seems as a lot of information is missing on the site for me, and I'm not finding the study cycle that you refer to - only this...
Awesome advice on the book, thanks a lot. I will be getting it.
As far as the equivalents of the math based subject I'm taking, I'm not sure I can give you an answer. A teacher that's worked at the university I attend is teaching with his own notes, and it's a 3 part course. 1st semester, 2nd...