Which statement describes inherent uncertainty in forecasting?

• A. Forecasts are always exact; no error
• B. Errors can be eliminated by larger sample
• C. All forecasts contain some degree of error due to randomness, measurement noise, or unobserved variables
• D. Forecast accuracy is constant over time

Answer: (C)

Forecasting always involves some uncertainty because the future is influenced by random variation and information gaps. There are multiple sources of error: randomness in the process being forecast, measurement noise in the data, and variables that affect the outcome but are not observed or included in the model. Even with a perfectly specified model and large data sets, these factors ensure that forecasts cannot be exact. Increasing sample size reduces sampling error but does not eliminate these other error sources. Additionally, forecast accuracy typically changes over time as relationships evolve or regime changes occur, so it is not constant. Therefore, the statement that all forecasts contain some degree of error due to randomness, measurement noise, or unobserved variables best captures inherent uncertainty in forecasting.