Business Statistics

462 Business Statistics

Computation of Sx, Sy, Sx

2

, and Sxy for Example 14.1

Months Advertisement

(in thousand ru-

pees): x

Sales (in thousand

rupees): y

x

2

xy

Jan 92 930 8464 85,560

Feb 94 900 8836 84,600

Mar 97 1020 9409 98,940

Apr 98 990 9604 97,020

May 100 1100 10,000 110,000

Jun 102 1050 10,404 107,100

Jul 104 1150 10,816 119,600

Aug 105 1120 11,025 117,600

Sep 105 1130 11,025 118,650

Oct 107 1200 11,449 128,400

Nov 107 1250 11,449 133,750

Dec 110 1220 12,100 134,200

Sx = 1221 Sy = 13,060 Sx

2

= 124,581 Sxy = 1,335,420

( )( )

(1221) (13,060)

1,335,420 6565

12

×

= − =

− =

∑ ∑

∑

xy

x y

SS xy

n

( )

2

2

2

(1221)

124,581 344.25

12

= − = − =

∑

∑

xx

x

SS x

n

1

6565

19.07

344.25

= = =

xy

xx

SS ...