POLREG Process

To access this process:

Sample Analysis ribbon >> Statistics Processes >> Polynomial Regression.
Enter "POLREG" into the Command Line and press ENTER.
Display the Find Command screen, locate POLREG and click Run.

See this process in the Command Table.

Process Overview

Polynomial regression. The polynomial fitted is up to the 5th order, and thus includes a regression line.

The polynomial is of the form:-

Y = C0 + C1*X + C2*X2 + C3*X3 + C4*X4 + C5*X5

where the coefficients C0, C1, C2, C3, C4 and C5 are written to the output file.

The input file must contain two explicit numeric fields *X and *Y. The polynomial is calculated as Y estimates for X values. There must be at least (order+1) points. If either the *X or *Y value is absent data in a particular record, the record is ignored. This allows regression polynomials to be computed on incomplete sets of data; for example original assays and a partial set of check assays.

DATAFILE: Name of the input data file.
XDATA: The X field in the input file that was used.
YDATA: The Y field in the input data file that was used.
GOODNFIT: The goodness of fit.
CORRCOEF: The coefficient of variance.
STDERR: The standard error.

Input Files

Name	Description	I/O Status	Required	Type
IN	Input file.	Input	Yes	Undefined

Output Files

Name	I/O Status	Required	Type	Description
OUT	Output	No	Undefined	Output file containing the coefficients.

Fields

Name	Description	Source	Required	Type	Default
X	X co-ordinate of the sample data.	IN	Yes	Numeric	X
Y	Y co-ordinate of the sample data.	IN	Yes	Numeric	Y

Parameters

Name	Description	Required	Default	Range	Values
ORDER	Order of the polynomial required (1,2,3,4 or 5).	Yes	1	1,5	1,2,3,4,5
PRINT	If set to 1 then a table of estimated values, based on the regression equation, will be written to the Command window. The default is (0), do not create the table.	No	0	0,1	0,1

Example

In the following example, a regression line is calculated for estimating P2O5 field values from FE field values in file assays.

Copy

!POLREG     &IN(ASSAYS),&OUT(COEFFS),*X(FE),*Y(P2O5),@ORDER=1

Error and Warning Messages

Message	Description
>>> ORDER CANNOT BE LESS THAN 1, ORDER=1 HAS BEEN ASSUMED <<<	A value of @ORDER below the minimum permitted value has been entered. The value is reset to the minimum and processing continues.
>>> ORDER CANNOT BE GREATER THAN 5, ORDER=5 HAS BEEN ASSUMED <<<	A value of @ORDER above the maximum permitted value has been entered. The value is reset to the maximum and processing continues.
>>> FIELD nnnnnnnn IS NOT NUMERIC <<< >>> ERR 120 <<< ( fileno) IN POLREG	Either the X or Y fields were not numeric. Fatal; the process is exited.
>>> TOO LITTLE DATA, CANNOT COMPUTE POLYNOMIAL OF REQUIRED ORDER <<< >>> ERR 120 <<< ( fileno) IN POLREG	The minimum number of points required is @ORDER + 1. Fatal; the process is exited.
>>> ABSOLUTE VALUE OF DIV. IS LESS THAN OR EQUAL TO ZERO >>> ERR 501 <<< ( 0) IN DSLE	The matrix of data presented for solution was singular. The data is inappropriate. Warning; the process continues, but the results may be meaningless.