title: Time Series Analysis using ts.plot and abline()
body: <p>Please explain me which transformation should I be using in the below code to apply WN model.    </p>
  
  <p>Below is the code where difference is used, I did not use log() because the series is decaying :        </p>
  
  <pre><code>data &lt;- c(60088,48398,54687,43337,47839,43480,53297,46882,45387,47186,42794,43274,31486,29036,25242,21792,23699,19161)        
  
  diff_data &lt;- diff(data)       
  ts.plot(diff_data)       
  model_wn &lt;- arima(diff_data, order = c(0, 0, 0))              
  coeff&lt;-model_wn$coef             
  ts.plot(data)             
  abline(0, coeff)             
  </code></pre>
  
  <p>Please explain me two things:</p>
  
  <ol>
  <li>with ts.plot and abline, the abline is not visible in the graph</li>
  <li>what can I utilise using the time series analysis with the above data.</li>
  </ol>