one queries so sxx/syy/ product correlation coefficient /sxy what do they get affected by ? what does mean and S.d get affected by?
PMCC is a measure of how close to perfect correlation the data is. If the data becomes more like the trend, or veers away from the trend, PMCC'll change. r = +1 is perfect correlation.
mean and std dev. OK there's a question that always comes up, to make sure ppl understand mean and std dev.
Imagine there's a set of data. Now if I decided that every value in that data should increase by 5, how would the mean and std dev be affected?
PMCC is a measure of how close to perfect correlation the data is. If the data becomes more like the trend, or veers away from the trend, PMCC'll change. r = +1 is perfect correlation.
mean and std dev. OK there's a question that always comes up, to make sure ppl understand mean and std dev.
Imagine there's a set of data. Now if I decided that every value in that data should increase by 5, how would the mean and std dev be affected?
i am sure the mean would increase and the S.D would decrease? i dont get the PMCC so does it not get affected at all?
i am sure the mean would increase and the S.D would decrease? i dont get the PMCC so does it not get affected at all?
mean would also increase by 5. Std dev WOULD NOT CHANGE AT ALL. This (and variations of what I've just said) always comes up. Remember this. When you change each value by the same amount, the std dev or variance does not change.
PMCC is how close to perfect correlation a set of data is. You'll have been given equations for working it out, and taught how to get it on a graphical calculator by putting in data.
this is a really great image that tells you what I mean, product moment correlation coefficient is r:
mean would also increase by 5. Std dev WOULD NOT CHANGE AT ALL. This (and variations of what I've just said) always comes up. Remember this. When you change each value by the same amount, the std dev or variance does not change.
PMCC is how close to perfect correlation a set of data is. You'll have been given equations for working it out, and taught how to get it on a graphical calculator by putting in data.
this is a really great image that tells you what I mean, product moment correlation coefficient is r:
yes i got it know so SD stays the same right but mean increases and how about sxx/syy/sxy?
yes i got it know so SD stays the same right but mean increases and how about sxx/syy/sxy?
yes mean increases because the mean is the average of the results, if each one goes up by 5, the mean'll go up by 5.
Std dev/variance, is how close to the mean the data tends to be, so if all of em increase by the same amount, they haven't actually moved any further from the mean, because the mean increases too... hope that makes sense.
What do you know about sxx, syy, sxy already? Do you know how to calculate them? You know you use those to calculate r (PMCC)
in ocr, we don't go too deep into what they actually mean, we just calculate sxx syy...
yes mean increases because the mean is the average of the results, if each one goes up by 5, the mean'll go up by 5.
Std dev/variance, is how close to the mean the data tends to be, so if all of em increase by the same amount, they haven't actually moved any further from the mean, because the mean increases too... hope that makes sense.
What do you know about sxx, syy, sxy already? Do you know how to calculate them? You know you use those to calculate r (PMCC)
in ocr, we don't go to deep into what they actually mean, we just calculate sxx syy...
yep i know how to calculate them and to find PMCC easy
if all data increases by the same amount, r wouldn't change, I don't really know if sxx etc will change, I just know the correlation will remain the same.
if all data increases by the same amount, r wouldn't change, I don't really know if sxx etc will change, I just know the correlation will remain the same.