The following example demonstrates the VARIANCE, COVARIANCE and CORRELATION functions to analyze grid points. It also shows the technique of putting the CrossTab into a MACRO, calling the MACRO to generate the specific result for a given dataset.
pointRec := { REAL x, REAL y };
analyze( ds ) := MACRO
#uniquename(rec)
%rec% := RECORD
c := COUNT(GROUP),
sx := SUM(GROUP, ds.x),
sy := SUM(GROUP, ds.y),
sxx := SUM(GROUP, ds.x * ds.x),
sxy := SUM(GROUP, ds.x * ds.y),
syy := SUM(GROUP, ds.y * ds.y),
varx := VARIANCE(GROUP, ds.x);
vary := VARIANCE(GROUP, ds.y);
varxy := COVARIANCE(GROUP, ds.x, ds.y);
rc := CORRELATION(GROUP, ds.x, ds.y) ;
END;
#uniquename(stats)
%stats% := TABLE(ds,%rec% );
OUTPUT(%stats%);
OUTPUT(%stats%, { varx - (sxx-sx*sx/c)/c,
vary - (syy-sy*sy/c)/c,
varxy - (sxy-sx*sy/c)/c,
rc - (varxy/SQRT(varx*vary)) });
OUTPUT(%stats%, { 'bestFit: y='+(STRING)((sy-sx*varxy/varx)/c)+' + '+(STRING)(varxy/varx)+'x' });
ENDMACRO;
ds1 := DATASET([{1,1},{2,2},{3,3},{4,4},{5,5},{6,6}], pointRec);
ds2 := DATASET([{1.93896e+009, 2.04482e+009},
{1.77971e+009, 8.54858e+008},
{2.96181e+009, 1.24848e+009},
{2.7744e+009, 1.26357e+009},
{1.14416e+009, 4.3429e+008},
{3.38728e+009, 1.30238e+009},
{3.19538e+009, 1.71177e+009} ], pointRec);
ds3 := DATASET([{1, 1.00039},
{2, 2.07702},
{3, 2.86158},
{4, 3.87114},
{5, 5.12417},
{6, 6.20283} ], pointRec);
analyze(ds1);
analyze(ds2);
analyze(ds3);