[R] Correlations not in sync with r2 from regression

2006-11-15 Thread Leeds, Mark \(IED\)
I have two variables, minutereturnsa which can be thought of as my
independent variable and minutereturnsb which can be thought of as my
dependent variable. When I run correlations on the two variables,
depending on which of the three methods I use, I get values of between
-.15 through -.19.
 
Then, when I do a regression, I get an rsquared of .004 which is more in
line with my intuition. In other words, I think the cor
function is doing something very different from what a regression
calculates. In fact, when I use my full data set ( not
included here ), I get correlations at the level of -0.97 which is
extremely unreasonable given the two variables. So, I think cor is 
calculating something else in terms of what I  am used to ? Or, maybe
the scale of my variables is too small and this could be causing
something to go wrong ?

Has anyone else had this experience where their value from a corr is
extremely high and yet the x y plot of the data and the regression
itself do not reflect this. All the code is below the two data sets in
case anyone wants to run it in order to see better what
I mean. It's probably just an non understanding on my part of what the
cor function is actually doing ? Thanks a lot.


minutereturnsa-c(-2.36264407318387e-05, -0.000114546483004574,
0.000480296012887571, 
-3.4370702667097e-05, -1.75028713567116e-05, -4.48227082969765e-05, 
2.90329205787643e-05, 0.000305825164510942, -5.03948020931233e-05, 
-0.000132337254829196, 0.000257366609910825, -0.000143416497692783, 
7.75575880389567e-05, -0.000390396184700492, 5.8463592766067e-05, 
-0.000166182789493874, 2.60897827946138e-05, -9.68285203182262e-05, 
0.000306300707090479, -0.000212593666131689, -2.05973305682505e-05, 
-0.000892262006425781, -7.65296399478643e-05, 9.29686476904834e-05, 
0.000400462742000229, -5.68981524482481e-05, 8.75374496889236e-06, 
-0.000325482754985451, -0.00026561900794686, 6.6048490682924e-05, 
5.22638320941127e-05, -9.67113649918971e-05, 2.9231547120645e-05, 
-5.85151902221526e-06, -6.50840736984293e-05, 3.34530686902923e-05, 
9.92970200188736e-05, 4.57716366808469e-05, 3.98160204646558e-05, 
-6.00275310205234e-05, -0.000182345705006526, -8.2237112582817e-05, 
8.49939625151563e-05, -3.54341054409346e-05, -0.000100100119395208, 
-0.000480874457688962, -5.96482127885878e-05, -1.57319826001867e-05, 
-0.000144679725631036, -0.000135114371429879, -4.7961402529495e-06, 
-0.000169457716609145, 3.99966377280236e-05, -5.124402520984e-05, 
0.000328975614625193, -0.00025080739315797, -0.000573125487459691, 
-7.7472898995623e-05, 3.44346931751005e-05, -3.06202186477478e-05, 
0.000370039560674940, 7.8350343693856e-05, -3.16439540668512e-05, 
-0.000160178561449342, -0.000396591758462961, -0.000210859243796158, 
0.000388855276420408, -0.000179700371241154, 4.16133481957459e-05, 
1.41192273312996e-05, 7.08468899466297e-05, -1.52706151546056e-06, 
3.67659444577839e-05, -0.000234283509586319, 0.000137243567309930, 
-5.20968533468391e-05, -0.000134271000559849, 0.00015686727434705, 
-1.20143299762177e-05, 0.000101875337767510, 3.65842929905824e-06, 
4.69929868991414e-05, 5.7532628616741e-05, -4.97275753463811e-06, 
-0.000170415848516292, 3.72182099566132e-05, -3.63157298233219e-05, 
6.5485377211516e-05, 1.70517614943577e-05, -0.0004420425496, 
0.000117663889794173, -0.000156675474467072, -9.45186652945296e-06, 
0.000228093804488516, -0.00018346543434, 8.7116036074697e-05, 
-0.000105286831582063, 3.77385685590426e-05, 0.000229830364734340, 
7.83212236301623e-05)

minutereturnsb-c(8.4645336092315e-05, 0.000342545113518611,
0.000619138432391253, 
2.39224895137724e-05, -0.000105430737374235, -4.64094877949961e-05, 
0.000232692295488945, 0.000170343242044346, -0.000278101637244177, 
-2.39061360733928e-05, -0.000308615318143524, 0.00088876749136002, 
8.32424077339411e-05, -0.00055346752090557, 8.45076374274e-05, 
-0.00054551438959205, 0.000259390072846699, 0.000144324272249641, 
0.000180899432469239, 0.000288664295990948, 9.95638801164489e-05, 
0.00097571036608901, -4.60863646098986e-05, -0.00047897519405371, 
5.14178471453519e-05, 2.4281687986516e-05, 0.00036058584985188, 
0.000134937727959361, 0.000103280488242596, 2.88151877292364e-05, 
-0.000310955520890666, 0.000106216873712484, 5.52294891624783e-05, 
5.71829552473702e-05, 0, -4.24836809553852e-06, -0.000112243149114732, 
-0.000225054512974054, -0.000127369605538163, -4.718171803475e-06, 
0.000575331719490535, 0.000414750691947852, -2.48462938587934e-05, 
-0.000508280783423132, 0.000246095358950704, -0.000407474448815393, 
0.000288693409606466, -7.07108562671976e-05, -0.000794312866452707, 
-0.000106260214363552, 0.00028805175686486, 7.4386971687268e-05, 
-0.000298442739602223, 0.000194096767056173, -0.000298344525328176, 
0.000220745065718120, 0.000709521706545146, -0.000217011729104044, 
-1.82252827203300e-05, -0.000385731348574225, 0.000332978442621368, 
-8.95786863042147e-05, 0.000104547275809885, -0.000295648677070659, 
-9.6397420641381e-06, 0.000224064465289331, 

Re: [R] Correlations not in sync with r2 from regression

2006-11-15 Thread Leeds, Mark \(IED\)
oops, I forgot to square !! Thanks Chuck. I would have
spent the rest of the day and then some trying to figure that one out




-Original Message-
From: Chuck Cleland [mailto:[EMAIL PROTECTED] 
Sent: Wednesday, November 15, 2006 11:46 AM
To: Leeds, Mark (IED)
Subject: Re: [R] Correlations not in sync with r2 from regression

Mark:
  cor() and R^2 are in sync for me on the data you provided:

 summary(lm(minutereturnsa ~ minutereturnsb))$r.squared
[1] 0.03640094

 summary(lm(minutereturnsa ~ minutereturnsb))$r.squared^.5
[1] 0.1907903

 cor(minutereturnsa, minutereturnsb)
[1] -0.1907903

 cor(minutereturnsa, minutereturnsb)^2
[1] 0.03640094

  I suspect you are doing different things with missing values in cor()
versus lm().

hope this helps,

Chuck

Leeds, Mark (IED) wrote:
 I have two variables, minutereturnsa which can be thought of as my 
 independent variable and minutereturnsb which can be thought of as my 
 dependent variable. When I run correlations on the two variables, 
 depending on which of the three methods I use, I get values of between
 -.15 through -.19.
  
 Then, when I do a regression, I get an rsquared of .004 which is more 
 in line with my intuition. In other words, I think the cor function is

 doing something very different from what a regression calculates. In 
 fact, when I use my full data set ( not included here ), I get 
 correlations at the level of -0.97 which is extremely unreasonable 
 given the two variables. So, I think cor is calculating something else

 in terms of what I  am used to ? Or, maybe the scale of my variables 
 is too small and this could be causing something to go wrong ?
 
 Has anyone else had this experience where their value from a corr is 
 extremely high and yet the x y plot of the data and the regression 
 itself do not reflect this. All the code is below the two data sets in

 case anyone wants to run it in order to see better what I mean. It's 
 probably just an non understanding on my part of what the cor function

 is actually doing ? Thanks a lot.
 
 
 minutereturnsa-c(-2.36264407318387e-05, -0.000114546483004574, 
 0.000480296012887571, -3.4370702667097e-05, -1.75028713567116e-05, 
 -4.48227082969765e-05, 2.90329205787643e-05, 0.000305825164510942, 
 -5.03948020931233e-05, -0.000132337254829196, 0.000257366609910825, 
 -0.000143416497692783, 7.75575880389567e-05, -0.000390396184700492, 
 5.8463592766067e-05, -0.000166182789493874, 2.60897827946138e-05, 
 -9.68285203182262e-05, 0.000306300707090479, -0.000212593666131689, 
 -2.05973305682505e-05, -0.000892262006425781, -7.65296399478643e-05, 
 9.29686476904834e-05, 0.000400462742000229, -5.68981524482481e-05, 
 8.75374496889236e-06, -0.000325482754985451, -0.00026561900794686, 
 6.6048490682924e-05, 5.22638320941127e-05, -9.67113649918971e-05, 
 2.9231547120645e-05, -5.85151902221526e-06, -6.50840736984293e-05, 
 3.34530686902923e-05, 9.92970200188736e-05, 4.57716366808469e-05, 
 3.98160204646558e-05, -6.00275310205234e-05, -0.000182345705006526, 
 -8.2237112582817e-05, 8.49939625151563e-05, -3.54341054409346e-05, 
 -0.000100100119395208, -0.000480874457688962, -5.96482127885878e-05, 
 -1.57319826001867e-05, -0.000144679725631036, -0.000135114371429879, 
 -4.7961402529495e-06, -0.000169457716609145, 3.99966377280236e-05, 
 -5.124402520984e-05, 0.000328975614625193, -0.00025080739315797, 
 -0.000573125487459691, -7.7472898995623e-05, 3.44346931751005e-05, 
 -3.06202186477478e-05, 0.000370039560674940, 7.8350343693856e-05, 
 -3.16439540668512e-05, -0.000160178561449342, -0.000396591758462961, 
 -0.000210859243796158, 0.000388855276420408, -0.000179700371241154, 
 4.16133481957459e-05, 1.41192273312996e-05, 7.08468899466297e-05, 
 -1.52706151546056e-06, 3.67659444577839e-05, -0.000234283509586319, 
 0.000137243567309930, -5.20968533468391e-05, -0.000134271000559849, 
 0.00015686727434705, -1.20143299762177e-05, 0.000101875337767510, 
 3.65842929905824e-06, 4.69929868991414e-05, 5.7532628616741e-05, 
 -4.97275753463811e-06, -0.000170415848516292, 3.72182099566132e-05, 
 -3.63157298233219e-05, 6.5485377211516e-05, 1.70517614943577e-05, 
 -0.0004420425496, 0.000117663889794173, -0.000156675474467072, 
 -9.45186652945296e-06, 0.000228093804488516, -0.00018346543434, 
 8.7116036074697e-05, -0.000105286831582063, 3.77385685590426e-05, 
 0.000229830364734340,
 7.83212236301623e-05)
 
 minutereturnsb-c(8.4645336092315e-05, 0.000342545113518611, 
 0.000619138432391253, 2.39224895137724e-05, -0.000105430737374235, 
 -4.64094877949961e-05, 0.000232692295488945, 0.000170343242044346, 
 -0.000278101637244177, -2.39061360733928e-05, -0.000308615318143524, 
 0.00088876749136002, 8.32424077339411e-05, -0.00055346752090557, 
 8.45076374274e-05, -0.00054551438959205, 0.000259390072846699, 
 0.000144324272249641, 0.000180899432469239, 0.000288664295990948, 
 9.95638801164489e-05, 0.00097571036608901, -4.60863646098986e-05, 
 -0.00047897519405371, 5.14178471453519e-05, 2.4281687986516e