Question

Known data in 2005 in the following table.

Month (t)	Request in unit (Y)
Jan	199
Feb	202
Mar	199
Apr	208
May	212
Jun	194
Jul	214
Aug	220
Sep	219
Oct	234
Nov	219
Dec	233

a. Determine the demand for 2007

b. Calculate the SSE (Sum of Squared Errors) and the SEE (Standard Error Estimated)

c. Define Confidence Interval and Prediction Interval with t = 18 and degrees ?= 0.01

Answer 1

a.

From the above diagram we see that (t,y_t) is linearly related.

Let Jan=1, Feb=202, Mar=3, Apr=4, May=5, Jun=6, Jul=7, Aug=8, Sep=9, Oct=10, Nov=11, Dec=12.

t*= 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12

t= 2(t*-6.5)=  -11, -9, -7, -5, -3, -1, 1, 3, 5, 7, 9, 11

y_t= 199, 202, 199, 208, 212, 194, 214, 220, 219, 234, 219, 233

Let trend equation

For computing the demand for 2007 t=37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59

The Demand for 2007: (Jan 2007, 268.99), (Feb 2007, 272.03), (Mar 2007, 275.07), (Apr 2007, 278.11), (May 2007, 281.15), (Jun 2007, 284.19), (Jul 2007, 287.23), (Aug 2007, 290.27), (Sep 2007, 293.31), (Oct 2007, 296.35), (Nov 2007, 299.39), (Dec 2007, 302.43)

b.