If you force the slope, it is no longer a regression, so no. It is best to add those other dependent variables to the regression and evaluate whether their presence causes the fit to improve and yield signs of coefficients that match what you expect.
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Sent from my phone. Please excuse my brevity.

J S <yulya258@gmail.com> wrote:

Dear forum members,



How can I force a negative slope in a linear regression even though the
slope might be positive?



I will need it for the purpose of determining the trend due reasons other
than biological because the biological (genetic) trend is not positive for
these data.



Thanks. Julia




Example of the data:



[1] 1.254 1.235 1.261 0.952 1.202 1.152 0.801 0.424 0.330 0.251 0.229 0.246

[13] 0.414 0.494 0.578 0.628 0.514 0.594 0.827 0.812 0.629 0.928 0.707 0.976

[25] 1.099 1.039 1.272 1.398 1.926 1.987 2.132 1.644 2.174 2.453 2.392 3.002

[37] 3.352 2.410 2.206 2.692 2.653 1.604 2.536 3.070 3.137 4.187 4.803 4.575

[49] 4.580 3.779 4.201 5.685 4.915 5.929 5.474 6.140 5.182 5.524 5.848 5.830

[61] 5.800 7.517 6.422

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