In: Operations Management
you can see in the following table, demand for heart transplant surgery at Washington General Hospital has increased steadily in the past few years:
Year 1 2 3 4 5
Heart Transplants 48.0 48.0 53.0 57.0 57.0
Year 1 2 3 4 5
Heart Transplants 44.0
The director of medical services predicted 6 years ago that demand in year 1 would be 44.0 sureries.
A) using exponential smoothing with a of 60.0 anf the given forecast for year 1, the forecasts for 2 years through 6 are? (round your answers to one decimal place)
For the forecast made using expotienal smoothing with a=60.0 and the given forecasts for year 1, MAD= _ surgeries (round your response to one decimal place)
Using expotiental smoothing with a of 90.0 and the given forecast for year 1, the forcasts for years 2 through 6 are (round your responses to one decimal place)
For the forecast made using expotiental smoothing with a=0.90 and given forecast for year 1, MAD= _ surgeries (round your response to one decimal place)
b) forecasts for years 4 through 6 using a 3 year moving average are? (round your response to one decimal place)
For forecast made using a 3 year moving average MAD = _ surgeries (round your answer to one decimal place)
C) forecasts for years 1 through 6 using the trend-projection method are (round your response to one decimal place)
For forecasts made using the trend-projection method, MAD= _ surgeries (round your response to one decimal place)
D) based on the comparison of MAD, the best forecast is archived using the _ method
FORECAST(T + 1) = FORECAST + (ALPHA * (ACTUAL DEMAND - FORECAST))
FORECAST 2 = 44 + (0.6 * (48 - 44) = 46.4
FORECAST 3 = 46.4 + (0.6 * (48 - 46.4) = 47.4
FORECAST 4 = 47.4 + (0.6 * (53 - 47.4) = 50.8
FORECAST 5 = 50.8 + (0.6 * (57 - 50.8) = 54.5
FORECAST 6 = 54.5 + (0.6 * (57 - 54.5) = 56
FORECAST ERROR
PERIOD |
ACTUAL DEMAND |
FORECAST |
DEVIATION(D - F) |
ABS DEVIATION |
1 |
48 |
44 |
4 |
4 |
2 |
48 |
46.4 |
1.6 |
1.6 |
3 |
53 |
47.4 |
5.6 |
5.6 |
4 |
57 |
50.8 |
6.2 |
6.2 |
5 |
57 |
54.5 |
2.5 |
2.5 |
SIGMA |
19.9 |
19.9 |
MAD = SIGMA(ABSOLUTE DEVIATION) / N, WHERE N = 5
MAD = 19.9 / 5 = 4.0
2. USING ALPHA = 0.9
FORECAST(T + 1) = FORECAST + (ALPHA * (ACTUAL DEMAND - FORECAST))
FORECAST 2 = 44 + (0.9 * (48 - 44) = 47.6
FORECAST 3 = 47.6 + (0.9 * (48 - 47.6) = 48
FORECAST 4 = 48 + (0.9 * (53 - 48) = 52.5
FORECAST 5 = 52.5 + (0.9 * (57 - 52.5) = 56.6
FORECAST 6 = 56.6 + (0.9 * (57 - 56.6) = 57
PERIOD |
ACTUAL DEMAND |
FORECAST |
DEVIATION(D - F) |
ABS DEVIATION |
1 |
48 |
44 |
4 |
4 |
2 |
48 |
47.6 |
0.4 |
0.4 |
3 |
53 |
48 |
5 |
5 |
4 |
57 |
52.5 |
4.5 |
4.5 |
5 |
57 |
56.6 |
0.4 |
0.4 |
SIGMA |
14.3 |
14.3 |
MAD = SIGMA(ABSOLUTE DEVIATION) / N, WHERE N = 5
MAD = 14.3 / 5 = 2.9
3. LINEAR REGRESSION
PERIOD (X) |
DEMAND (Y) |
X |
Y |
X * Y |
X^2 |
1 |
48 |
1 |
48 |
48 |
1 |
2 |
48 |
2 |
48 |
96 |
4 |
3 |
53 |
3 |
53 |
159 |
9 |
4 |
57 |
4 |
57 |
228 |
16 |
5 |
57 |
5 |
57 |
285 |
25 |
SIGMA |
15 |
263 |
816 |
55 |
INTERCEPT = (SIGMA(Y) * SIGMA(X^2) - SIGMA(X) * SIGMA(XY)) / (N * SIGMA(X^2) - SIGMA(X)^2)
INTERCEPT = (263 * 55) - (15 * 816) / ((5 * 55) - 15^2) = 44.5
SLOPE = ((N * SIGMA(XY)) - (SIGMA(X) * SIGMA(Y))) - (N * SIGMA(X^2) - SIGMA(X)^2)
SLOPE = ((5 * 816) - (15 * 263) / ((5 * 55) - 15^2) = 2.7
LINE EQUATION = A + B(x), WHERE A IS THE INTERCEPT, B IS THE SLOPE, x IS THE PERIOD = 44.5 + (2.7 * X)
FOR THE VALUE OF X = 6 FORECAST = 44.5 + (2.7 * 6) = 60.7
FORECAST ERROR
PERIOD |
ACTUAL DEMAND |
FORECAST |
DEVIATION(D - F) |
ABS DEVIATION |
1 |
48 |
47.2 |
0.8 |
0.8 |
2 |
48 |
49.9 |
-1.9 |
1.9 |
3 |
53 |
52.6 |
0.4 |
0.4 |
4 |
57 |
55.3 |
1.7 |
1.7 |
5 |
57 |
58 |
-1 |
1 |
SIGMA |
0 |
5.8 |
MAD = SIGMA(ABSOLUTE DEVIATION) / N, WHERE N = 5
MAD = 5.8 / 5 = 1.2
4.
SIMPLE MOVING AVERAGE
FORECAST = SIGMA(PREVIOUS N DEMANDS) / N
WHERE N = 2
FORECAST 3 = (48 + 48) / 2 = 48
FORECAST 4 = (48 + 53) / 2 = 50.5
FORECAST 5 = (53 + 57) / 2 = 55
FORECAST 6 = (57 + 57) / 2 = 57
PERIOD |
ACTUAL DEMAND |
FORECAST |
DEVIATION(D - F) |
ABS DEVIATION |
1 |
48 |
|||
2 |
48 |
|||
3 |
53 |
48 |
5 |
5 |
4 |
57 |
50.5 |
6.5 |
6.5 |
5 |
57 |
55 |
2 |
2 |
SIGMA |
13.5 |
13.5 |
MAD = SIGMA(ABSOLUTE DEVIATION) / N, WHERE N = 3
MAD = 13.5 / 3 = 4.5
5. USING LINEAR REGRESSION PROVIDES THE LOWEST MAD VALUE AND IS THEREFORE BETTER.
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