title: Treating binary variables for first difference method to solve autocorrelation issue
body: <p>I have an autocorrelation problem in my panel data.
  So I decided to use first difference method so deal with this problem.</p>
  
  <p>Most of my independent variables are binary.
  So if I do the finite difference method over this,
  I get -1, 0, and 1 instead of 0 or 1 as before.</p>
  
  <p>Is this ok?</p>
  
  <p>Besides, my data set time flow is as follows which I am not sure how I can apply first difference method in this case when I have multiple difference incidents happening on the same day:</p>
  
  <pre><code>     Date   ID  X   Y   Z   L   M   A   B   C   D   E
   01/01/2017 A   0   1   0   0   0   0   1   0   0   7.8
   01/01/2017 A   0   1   0   0   0   1   0   0   1   6.5
   01/01/2017 B   0   0   0   0   1   1   0   0   1   6.5
   01/03/2017 A   0   1   0   0   0   0   0   0   0   7.8
   01/04/2017 C   0   0   1   0   0   1   0   0   0   6.5
   01/04/2017 C   0   0   0   0   0   0   1   0   0   7.3
  </code></pre>
  
  <p>I sort this again according to Date and ID which become as follows:</p>
  
  <pre><code>    Date    ID  X   Y   Z   L   M   A   B   C   D   E
   01/01/2017 A   0   1   0   0   0   0   1   0   0   7.8
   01/01/2017 A   0   1   0   0   0   1   0   0   1   6.5
   01/01/2017 B   0   0   0   0   1   1   0   0   1   6.5
   01/03/2017 A   0   1   0   0   0   0   0   0   0   7.8
   01/04/2017 C   0   0   1   0   0   1   0   0   0   6.5
   01/04/2017 C   0   0   0   0   0   0   1   0   0   7.3
  </code></pre>
  
  <p>Besides, Is this new data sorting ok to use in my Panel regression and also take the first difference over this utilizing this row sequence?</p>