Plantcity is a large nursery and retail store specializing in house and garden plants and supplies. Jean

Question:

Plantcity is a large nursery and retail store specializing in house and garden plants and supplies. Jean Raouth, the assistant manager, is in the process of budgeting monthly supplies expense for 2010. She assumes that in some way supplies expense is related to sales, either in units or in dollars. She has collected these data for sales and supplies expenses for June 2007 through December 2009, and has estimated sales for 2010:


Date	Supplies Expense	Sales Units	Sales Dollars
June-07	$2,745	354	$2,009
July-07	$3,200	436	$2,190
August-07	$3,232	525	$2,878
September-07	$2,199	145	$1,856
October-07	$2,321	199	$2,168
November-07	$3,432	543	$2,152
December-07	$4,278	1,189	$2,463
January-08	$2,310	212	$1,999
February-08	$2,573	284	$2,190
March-08	$2,487	246	$1,894
April-08	$2,484	278	$2,134
May-08	$3,384	498	$3,210
June-08	$2,945	424	$2,850
July-08	$2,758	312	$2,265
August-08	$3,394	485	$2,435
September-08	$2,254	188	$1,893
October-08	$2,763	276	$2,232
November-08	$3,245	489	$3,004
December-08	$4,576	1,045	$3,309
January-09	$2,103	104	$2,195
February-09	$2,056	167	$2,045
March-09	$3,874	298	$2,301
April-09	$2,784	398	$2,345
May-09	$2,345	187	$1,815
June-09	$2,912	334	$2,094
July-09	$2,093	264	$1,934
August-09	$2,873	333	$2,054
September-09	$2,563	143	$1,977
October-09	$2,384	245	$1,857
November-09	$2,476	232	$2,189
December-09	$3,364	1,122	$3,433
January-10		180	$1,600
Feb-10		230	$2,000
March-10		190	$1,900
April-10		450	$2,400
May-10		350	$2,300
June-10		350	$2,300
July-10		450	$2,500
Aug-10		550	$3,000
Sept-10		300	$2,500
Oct-10		300	$2,500
Nov-10		450	$3,200
Dec-10		950	$3,900

Required
1. Develop the regression that Jean should use based on these data and use the regression procedure in Excel or an equivalent regression software program. Evaluate the reliability and precision of the regression you have chosen.
2. What are the predicted monthly figures for supplies expense for 2010?