Forecasting New Product Diffusion Using Grey Time-Delayed Verhulst Model

Table 2

Comparison of the modeling results.

Year	Actual values	Traditional grey; Verhulst model		Grey time-delayed; Verhulst model; (𝜏0=1); (improved model 1)		grey time-delayed; Verhulst model; (𝜏0=2); (improved model 2)
		𝑥^(0)(𝑘)	𝑒(𝑘) %	𝑥^(0)(𝑘)	𝑒(𝑘) %	𝑒(𝑘) %	𝑒(𝑘) %
2003	22	19.57	−11.02	—	—	—	—
2004	120	47.71	−60.24	89.74	−25.21	—	—
2005	750	115.12	−84.67	473.87	−36.82	474.88	−36.68
2006	1180	271.34	−77.01	1316.59	11.58	1311.33	11.13
2007	2120	607.03	−71.37	2097.95	−1.04	2100.21	−0.93
𝑒avg%		—	60.82	—	18.66	—	16.25
𝑝avg%		—	39.18	—	81.34	—	83.75