Abstract
ORTOPOL.BAS: A computer program for trend analysis and curves fitting by orthogonal polynomials. A QBASIC program for curve fitting for othogonal polynomials within experimental design is presented. It studies trend analysis, its significance and the proportion of explained variace and also the value of the coefficients for a priori orthogonal tests of differences between means. It is valid for the general case of unequally spaced and weighted treatment levels design.