Echlin Inc. is an after-market supplier of automotive spare parts. 0 A part is usually made specifically for a particular model of a car. In order to forecast the demand for a part, Echlin tries to use the following process: (a) determine the total number of new vehicles using this part sold each year, (b) determine the replacement probability by age for the first replacement, second replacement, and so on of the part for current and future years, (c) calculate the total number of replacement units for each year, (d) break this down into original equipment manufacturer market and aftermarket manufacturer market, (e) calculate Echlin€™s annual share using its market share, and, finally (f) break down the annual forecast into quarterly and monthly sales forecasts using seasonal relatives.
Consider a specific part. Echlin makes brake callipers for a particular model of a car, first introduced in 1986. Suppose it is now the end of 1992, and using steps a to e above Echlin has forecasted its own sales of this calliper for 1993.

Echlin also has quarterly sales of these calipers for the past three years.

a. Use the 1990-92 quarterly data above to determine the quarterly seasonal relatives.
b. Use your answer to part a and 1993 forecast sales (6,334 units) to forecast quarterly sales for 1993.
c. Deseasonalize the data, fit an appropriate model to the deseasonalized data, project it four quarters ahead, and reseasonalize the projections to forecast quarterly demand in 1993. Contrast your results with part (b).

Transcribed Image Text:

Year Eclin's Salos of Callipors 1990 1991 1992 1993 10,444 10,319 8,477 6,334 forecasf 1990 2370 2058 2778 3238 10,444 1991 2641 2198 2518 2962 0,319 Quarter 1992 2281 1814 2127 2255 8,477 02 Total