What type of variation in a time series is characterized by systematic change over a long period of time?

Trend variation in a time series refers to a systematic change that occurs over an extended period. This change can illustrate an increasing or decreasing pattern that reflects the underlying movement of the data points toward a specific direction. Unlike seasonal variation, which follows a regular pattern within specific periods (such as months or quarters), or random variation, which is erratic and lacks any predictable pattern, trend variation indicates a consistent long-term direction in the data.

Trend variation is often evaluated through methods such as regression analysis or moving averages, which allow analysts to identify the general direction of the data over time. By observing this long-term movement, businesses and researchers can make forecasts and strategic decisions based on the anticipated trajectory of the time series. In financial contexts, trend variation is particularly valuable, as it can inform investment strategies and operational planning.