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Mathematics Question Thread
fun_jirachi:
I wouldn't (since a is not strictly indexed) but it doesn't really matter either way (since a holds a constant value for all i).
neha.singh4:
Hello!
As apart of a maths assessment task I was wondering what were some examples of bivariate data where one pair of variables shows a
positive correlation and the other showing a negative correlation. For example, some that I have are: Arm Length vs Foot Length, Height and Running Speed but am looking for some other ones.
And also what kinds of predictions can you gather from data when interpolating and extrapolating values?
Thank you! Any help would be greatly appreciated!!!
fun_jirachi:
--- Quote from: neha.singh4 on July 03, 2021, 09:42:23 pm ---Hello!
As apart of a maths assessment task I was wondering what were some examples of bivariate data where one pair of variables shows a
positive correlation and the other showing a negative correlation. For example, some that I have are: Arm Length vs Foot Length, Height and Running Speed but am looking for some other ones.
And also what kinds of predictions can you gather from data when interpolating and extrapolating values?
--- End quote ---
These are good examples of positive correlation; was there anything in particular you were looking for for your examples? The question is pretty vague :(
Extrapolating is generally risky, since you can't always guarantee trends and correlation extend to a range values not within your measured range. Interpolation of bivariate data given one variable can allow you to predict with reasonable accuracy the other variable given a large enough sample size ie. P(Y|X) or P(X|Y).
neha.singh4:
--- Quote from: fun_jirachi on July 03, 2021, 10:20:32 pm ---These are good examples of positive correlation; was there anything in particular you were looking for for your examples? The question is pretty vague :(
Extrapolating is generally risky, since you can't always guarantee trends and correlation extend to a range values not within your measured range. Interpolation of bivariate data given one variable can allow you to predict with reasonable accuracy the other variable given a large enough sample size ie. P(Y|X) or P(X|Y).
--- End quote ---
Oh yes that makes sense! Thank you! : ))))
Yes I agree the question is pretty vague too. In terms of what my teacher had explained, she'd like for us to show one set of data that reveals a positive correlation and another set of data that reveals a negative correlation. I was looking for some examples where two sets of variables could fulfill this requirement as well as allow me to analyse data in terms of the Pearson's correlation. Any recommendations?
fun_jirachi:
If the question is that vague, you can literally choose anything. Your examples are more than good enough for a possible positive correlation. Most of the data you will be analysing I'd assume would be discrete, but you will always be able to analyse the data in terms of the Pearson correlation coefficient because you can always find the covariance and the variance of the data set(s). For negative correlation, consider some things that may be inversely proportional but not necessarily so, like hours spent on extra-curricular activities vs. grades.
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