   </td>
        <td><p>Missing Value Imputation by Kalman Smoothing and State Space Models</p></td>
      </tr><tr><td>
          <p><code><a href="na_locf.html">na_locf()</a></code> </p>
        </td>
        <td><p>Missing Value Imputation by Last Observation Carried Forward</p></td>
      </tr><tr><td>
          <p><code><a href="na_ma.html">na_ma()</a></code> </p>
        </td>
        <td><p>Missing Value Imputation by Weighted Moving Average</p></td>
      </tr><tr><td>
          <p><code><a href="na