please explain formula

Question

please explain what is ȳ in the formula R2 = 1- ∑(y-ŷ)2 ÷ ∑(y-ȳ)2. The formula is NOT complicated if you know what is what. Also tell what is it in the ice cream example

Answer 1

Sonja Simeonova Greetings & Welcome to Microsoft Q&A forum!

Could you please share more details about your ask? Which documentation are you referring to?

Are you following Microsoft Azure AI Fundamentals: AI Overview path?

From the given formula R2 = 1- ∑(y-ŷ)2 ÷ ∑(y-ȳ)2

Where y = actual values, ŷ= predicted values, ȳ= mean of actual values = 121/6 = 20.16666

R2 = 1- ∑(y-ŷ)2 ÷ ∑(y-ȳ)2

R2 = 1- 36 / 740.8336

R2 = 1-0.04859391

R2= 0.951

As given in the Learn Path document, R2 value is 0.95.

Where y = actual values, ŷ= predicted values, ȳ= mean of actual values = 121/6 = 20.16666 (Yes, you calculated correctly).

Reference: https://learn.microsoft.com/en-us/answers/questions/1608884/coefficient-of-determination-(r2)-fundamentals-of

Do let me know if that helps or have any other queries.

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