data one; input gdd ndvi yld; if gdd = 81 then intc_dif=0; if gdd = 113 then intc_dif=1; slop_dif=intc_dif*ndvi; cards; 81 0.361 2142.42 81 0.227 772.01 81 0.425 3285.61 81 0.440 2850.91 81 0.475 4684.25 81 0.450 4641.91 81 0.483 5315.12 81 0.355 2646.27 81 0.444 4358.23 81 0.467 4259.44 81 0.457 5277.02 81 0.476 5247.38 81 0.533 5384.28 81 0.454 4307.42 81 0.321 1589.17 81 0.393 1563.77 81 0.406 2745.06 81 0.513 2431.75 81 0.457 3240.45 81 0.478 5521.18 81 0.452 5483.07 81 0.377 3322.30 81 0.413 5233.26 81 0.469 5202.21 81 0.477 4966.52 81 0.442 5260.08 81 0.566 5629.85 81 0.442 5569.16 81 0.376 2273.68 81 0.438 2721.07 81 0.449 3908.01 81 0.458 4409.04 81 0.467 4811.27 81 0.494 5039.91 81 0.492 5387.10 81 0.397 4486.66 81 0.461 4980.63 81 0.451 4852.20 81 0.485 5346.17 81 0.486 5000.39 81 0.539 5325.00 81 0.482 4898.78 81 0.383 2248.27 81 0.434 2695.67 81 0.416 2852.33 81 0.501 3549.53 81 0.482 4948.17 81 0.537 5272.78 81 0.542 5267.14 81 0.416 4126.77 81 0.446 4698.36 81 0.498 5175.40 81 0.483 4222.74 81 0.488 5381.45 81 0.591 5377.22 81 0.477 5007.45 113 0.234 772.01 113 0.479 3285.61 113 0.514 2850.91 113 0.640 4684.25 113 0.682 4641.91 113 0.740 5315.12 113 0.468 2646.27 113 0.593 4358.23 113 0.655 4259.44 113 0.706 5277.02 113 0.673 5247.38 113 0.754 5384.28 113 0.640 4307.42 113 0.336 1589.17 113 0.444 1563.77 113 0.395 2745.06 113 0.519 2431.75 113 0.643 3240.45 113 0.725 5521.18 113 0.798 5483.07 113 0.539 3322.30 113 0.718 5233.26 113 0.699 5202.21 113 0.659 4966.52 113 0.752 5260.08 113 0.792 5629.85 113 0.689 5569.16 113 0.376 2273.68 113 0.416 2721.07 113 0.521 3908.01 113 0.614 4409.04 113 0.691 4811.27 113 0.724 5039.91 113 0.752 5387.10 113 0.551 4486.66 113 0.688 4980.63 113 0.740 4852.20 113 0.742 5346.17 113 0.654 5000.39 113 0.716 5325.00 113 0.659 4898.78 113 0.341 2248.27 113 0.377 2695.67 113 0.406 2852.33 113 0.545 3549.53 113 0.635 4948.17 113 0.735 5272.78 113 0.784 5267.14 113 0.578 4126.77 113 0.644 4698.36 113 0.693 5175.40 113 0.664 4222.74 113 0.700 5381.45 113 0.788 5377.22 113 0.681 5007.45 data two; set one; proc sort; by gdd; proc reg; model yld = ndvi intc_dif slop_dif; run; proc reg; by gdd; model yld=ndvi; run; /* LINEAR PLATEAU */ PROC NLIN DATA = ONE BEST = 3; PARMS B0=0.0 to 0.8 by 0.01 B1=0.4 to 0.8 by 0.001 NJOINT=0 to 100 by 1; IF X