Skip to content
START WITH A QUESTION

What would you like to understand?

Find an answer. See the moment it becomes clear. Follow the idea further.

← Concept directory

Answers for “在平滑常数为 0.2 的指数平滑中,如何计算下一个预测值?”

5 keyword matches

Understanding your question. You can explore the search results below now.

Find a method

↗

To calculate the next forecast, you use the weighted average form of the exponential smoothing formula: Ft+1=αAt+(1−α)FtF_{t+1} = \alpha A_t + (1 - \alpha)F_t. With a smoothing constant of α=0.2\alpha = 0.2, the formula becomes Ft+1=0.2(At)+0.8(Ft)F_{t+1} = 0.2(A_t) + 0.8(F_t).

Conditions: The smoothing constant is α=0.2\alpha = 0.2.; You know the actual sales value for the current period (AtA_t).; You know the forecast value for the current period (FtF_t).

Understand why

↗

There are two mathematically equivalent forms of the exponential smoothing formula. The first is the error correction form: Ft+1=Ft+α(At−Ft)F_{t+1} = F_t + \alpha(A_t - F_t).

Conditions: You are performing exponential smoothing calculations.; You want to understand the relationship between the two formula forms.

Find a method

↗

The intercept b0b_0 is calculated by substituting the mean point (xˉ,yˉ)(\bar{x}, \bar{y}) and the known slope b1b_1 into the regression equation y^=b0+b1x\hat{y} = b_0 + b_1x, and then solving algebraically for b0b_0. In the example, substituting x=3x=3, y^=4\hat{y}=4, and b1=0.6b_1=0.6 yields 4=b0+0.6(3)4 = b_0 + 0.6(3), which simplifies to b0=2.2b_0 = 2.2.

Conditions: The slope b1b_1 has already been computed.; The sample means xˉ\bar{x} and yˉ\bar{y} are known.; The regression line is assumed to pass through (xˉ,yˉ)(\bar{x}, \bar{y}).

Meet the concept

↗

If no forecast value for the first period is given, the standard assumption is to set the first forecast equal to the first actual value, expressed as F1=A1F_1 = A_1. This provides a starting point for the exponential smoothing calculations.

Conditions: No initial forecast value is provided for the first period.; You are beginning an exponential smoothing calculation.

Find a method

↗

To calculate the Mean Squared Error (MSE), you first find the forecast errors by subtracting the forecast from the actual sales for each period. Next, you square each of these errors.

Conditions: You have calculated the forecasts for each period.; You have the actual sales data for each period.; Errors are not calculated for the first period if F1=A1F_1 = A_1.