In exponential smoothing, the smoothing constant, typically denoted as \(\alpha\), is a value between 0 and 1. It determines the weight given to the most recent observation compared to the previous smoothed value. A higher value of \(\alpha\) gives more weight to recent observations, making the forecast more sensitive to recent changes, while a lower value makes the forecast more stable by giving more weight to past data.
Values of \(\alpha\) outside the range of 0 to 1 would make the smoothing process invalid, as the weightings would not make sense.