title: Dickey-Fuller test in Python
body: <p>I was trying to figure out exactly what the following expression means:</p>
  <h1>Perform Dickey-Fuller test:</h1>
  <pre><code>print 'Results of Dickey-Fuller Test:'
  dftest = adfuller(timeseries, autolag='AIC')
  dfoutput = pd.Series(dftest[0:4], index=['Test Statistic','p-value','#Lags Used','Number of Observations Used'])
  for key,value in dftest[4].items():
      dfoutput['Critical Value (%s)'%key] = value
  print dfoutput
  </code></pre>
  <p>More specifically what does this [0:4] represent?</p>