title: How to calculate R-squared in nls package (non-linear model) in R?
body: <p>I analyzed non-linear regression using nls package.</p>
  <pre><code>power&lt;- nls(formula= agw~a*area^b, data=calibration_6, start=list(a=1, b=1))
  summary(power)
  </code></pre>
  <p>I heard in non-linear model, R-squared is not valid and rather than R-squared, we usually show residual standard error which R provides</p>
  <p>However, I just want to know what R-squared is. Is that possible to check R-squared in nls package?</p>
  <p>Many thanks!!!</p>
  <ul>
  <li>OutPut</li>
  </ul>
  <p><a href="https://i.stack.imgur.com/2j0ox.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/2j0ox.jpg" alt="enter image description here" /></a></p>