Kalman Filter with Missing Data

The Kalman filter with missing data extends the classical Kalman filter to handle time series in which some observations are absent. When an observation is missing at time t the update step is skipped and the state estimate is carried forward from the prediction step alone. Combined with the Expectation-Maximisation (EM) algorithm, the approach also estimates unknown model parameters from incomplete data, making it a practical tool for real-world irregularly observed series.