What are the technical problems associated with time series?
The three main machine learning problems with time series are forecasting, classification, regression, and anomaly detection. In this section, we'll provide a broad overview of applications of time series and a history of machine learning and analysis techniques applied to time series.Common problem scenarios when dealing with time series data include:
- Forecasting: The use of a model to predict future values based on previously observed values. This technique is used to predict future values of the time series based on past values. This can be done using methods such as ARIMA or exponential smoothing.
- Decomposition: This technique is used to separate the data into its constituent parts such as trend, seasonality, and residuals. This can be done using methods such as additive or multiplicative decomposition. This involves trend analysis, where we identify long-term trends in a time series, and seasonality analysis, which is about identifying repeating patterns in a time series.
- Classification/Regression: This technique is used to predict a target variable based on the time series data. This can be done using methods such as support vector machines or logistic regression.
- Anomaly detection: Identifying unusual patterns (outliers) in a time series. Outliers are unusual observations that fall outside of the typical pattern.
- Clustering: This technique is used to group together similar time series. This can be done using methods such as k-means clustering.
- Drift detection: This technique is used to identify systematic changes in the time series data. This can be done using methods such as the Mann-Kendall test.
- Smoothing: This technique is used to remove the noise from the data. This can be done using a simple moving average or a more sophisticated technique such as exponential smoothing.
An example for forecasting is ARIMA modeling, where we are using autoregressive and moving average models to forecast future values in a time series. Which technique you use will depend on the nature of your data and the problem you are trying to solve.Multivariate forecasting is a natural extension of the univariate case, where the goal is to predict multiple variables simultaneously. For example, in a company, one might want to forecast sales, price, inventory, and production simultaneously. This can be done with a vector autoregression model, where each variable is predicted as a function of its own past values and the past values of the other variables. Multistep forecasting is a generalization of the univariate case, where the goal is to predict multiple steps into the future. For example, in a company, one might want to forecast sales for the next 6 months. This can be done with a vector autoregression model, where each variable is predicted as a function of its own past values and the past values of the other variables.