Page 275 - Industrial Process Plant Construction Estimating and Man Hour Analysis

254 Industrial process plant construction estimating and man-hour analysis

1400
Average man hour 1000
1200

800
600
400
200
0
1 2 3 4 5 6 7 8
Series1 Series2
FIG. 12.7.1 Simple moving average coal-fired power plant—weld casing seams.

The plot of forecast values (predict in red) smoothens out the plot of y values
(in blue) (Fig. 12.7.1).
The higher the value of m, the more smoothing that occurs.

Example 12.7.2
Using Example 1.3 (simple moving average); exponential smoothing with a = 0.2
(Table 12.7.2)
Data for input: Man-hours for the field erection of coal-fired power plant—
weld casing seams
Year (t): 2005, 2006, 2007, 2008, 2009, 2010, 2011, and 2012
Average man-hour (y): 1053, 988, 1020, 950, 1061, 1177, 892, and 1089

TABLE 12.7.2 Simple exponential smoothing forecast

Year Average man-hours
t y Predict e e 2
2005 1053 1053.0
2006 988 1053.0 -65.0 4225.0
2007 1020 1040.0 -20.3 412.1
2008 950 1035.9 -85.9 7385.7
2009 1061 1018.8 41.7 1742.9
2010 1177 1027.1 150.1 22529.5
2011 832 1057.1 -225.5 50832.8
2012 1089 1012.0 77.0 5924.5

Predict 8296.9
Alpha MAE MSE
0.2 -18.3 13293.2