title: How to do ANOVA for regression models in R?
body: <p>When I run ANOVA for the regression models which I develop, this error appears:</p>
  
  <pre><code>  Error in anova.nls(model3) : nova is only defined for sequences of "nls" objects
  </code></pre>
  
  <p>What is the meaning of this error?</p>
  
  <p>It should be mentioned that when I run summary of model, I see just parameters estimated for the model and no other statistical parameters. Does it mean that the model still needs modification and that is not the final model? please look at the instruction of my model, and the summary and ANOVA:</p>
  
  <pre><code> model3 = nls(Height ~ 1.30 + a*(I(1- exp(-b*Diameter))^c), data = dat1, start = list(a=48,b=0.012,c=0.491), algorithm="port")
  
   summary(model3)
   anova(model3)
  </code></pre>
  
  <p>Here are the result:</p>
  
  <pre><code>model3 = nls(Height ~ 1.30 + a*(I(1- exp(-b*Diameter))^c), data = dat1, start = list(a=48,b=0.012,c=0.491), algorithm="port")
  summary(model3)
  
  Formula: Height ~ 1.3 + a * (I(1 - exp(-b * Diameter))^c)
  
  Parameters:
     Estimate Std. Error t value Pr(&gt;|t|)    
  a 43.121923   1.653027  26.087  &lt; 2e-16 ***
  
  b  0.022037   0.003811   5.783 1.38e-08 ***
  
  c  0.914263   0.116202   7.868 2.75e-14 ***
  ---
  Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 
  
  Residual standard error: 5.369 on 446 degrees of freedom
  
  Algorithm "port", convergence message: relative convergence (4) 
  
  anova(model3)
  Error in anova.nls(model3) : 
    anova is only defined for sequences of "nls" objects
  </code></pre>
  
  <p>I am a beginner in R. Is there somebody who help me?
  Thank you</p>