title: Confidence intervals of fit function
body: <p>I'm trying to deal with interpretation of fitted curves.</p>
  
  <p>for the fitting purpose I use Matlab's <code>fit</code> function using predefined models (like <code>poly2</code>) or custom-defined (like <code>y=ax^4+bx^2+c</code>) without any problem.</p>
  
  <p>I would like to determine quality of each parameter (<code>a</code>, <code>b</code> and <code>c</code>) to be able to plot the data points (able), fitted curve (able) and the "area where the curve can be with a given probability" (unable).</p>
  
  <p>If I run  <code>foo=fit(x,y,'poly1')</code> <strong>without semicolon</strong>, the return is:</p>
  
  <pre><code>foo = 
  
   Linear model Poly1:
   fitNi(x) = p1*x + p2
   Coefficients (with 95% confidence bounds):
     p1 =       40.19  (3.088, 77.28)
     p2 =        1042  (730.1, 1354)
  </code></pre>
  
  <p>Question is, how can I dig the <code>3.088, 77.28</code> values? out of the <code>foo</code> which describe the confidence interval for <code>p1</code> parameter, I suppose.</p>