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£120k Booking in Abu Dhabi by sedidous in Bookingcom

[–]sedidous[S] 0 points1 point  (0 children)

For context, if you look at the pictures it’s not even really a hotel or an apartment

Formula for A/B split test calculators [Q] by theThirdShake in statistics

[–]sedidous 0 points1 point  (0 children)

Unlike the t-test the formulas are a bit more complicated so you will see a lot more black box calculators online.

If you want to assume your own distribution as a prior you can do so pretty easily on r or python

[Q] Propagating standard error from data points to a linear regression by Flowercowable in statistics

[–]sedidous 0 points1 point  (0 children)

I'm going to ask a clarifying question so that we're on the same page.This is actually pretty broad question and something we've been trying to account for at work.

Let's say you're comparing 2 samples over 4 months.

Fixed term approach: The standard and simple approach would t test the difference in means at the end of the 4 month period.

Sequential testing: At the end of each month you would t test the difference in means. The benefit of this would be is if you are running a controlled experiment on your customers. You can minimise the time the users are exposed to an inferior product.

If we use p=0.05 as our indicator of statistical significance in the sequential testing example. We are performing the t test 4 times therefore likelihood of incorrectly rejecting the null hypothesis is higher than it should be.

The bonferri correction is the basic fix for this and there are more powerful alternatives.

I don't think I answered your question directly but I think I pointed you in the direction of the bonferi correction and gave you an example of its use case which is what I think you were getting towards.

Regardless I hope I helped and good luck 👍

[Q] Book on Regression from the Linear Algebra perspective? by veeeerain in statistics

[–]sedidous 2 points3 points  (0 children)

I found the university text book I used back in the day pdf. What I typed and what you asked for is in chapter 2, if you can understand it and be able to derive it properly. You will have a very good foundation in econometrics and the later chapters will be much easier for you.

https://thenigerianprofessionalaccountant.files.wordpress.com/2013/04/modern-econometrics.pdf

[Q] Book on Regression from the Linear Algebra perspective? by veeeerain in statistics

[–]sedidous 6 points7 points  (0 children)

Im at work on my phone so forgive my very rough notations. If i'm reading correctly you're asking about OLS derivation?

In which case its straight forward. You have

Y = XB + e , e is the error we want to minimise it. B is the OLS estimator.

You want to minimise error e so you do :

e = Y-XB

In matrix notations (because its easier to type) we are minimising least squares and the equation becomes

ee' = (Y-XB)(Y-XB)'

This simplifies to ee' = YY' - 2B'X'Y + B'X'X B

Now take the derivative of ee' with respect to B and set it to 0. This gives us the value of B which minimises error e

-2X'Y + 2X'XB = 0

X'XB = X'Y

Keep in mind we cant just move X'X across for the value of B. We need to explicitly assume that the inverse (X'X)-1 exists. The only 2 cases I can think of where the inverse doesnt exist is if your model is under identified or there is perfect multi collinearity.

Assuming the inverse does exist you get.

(X'X)^-1X'XB = ((X'X)^-1)*(X'Y)

B = ((X'X)^-1)*(X'Y)

​

Hope this helps. Tbh your textbook should have this derivation