Texas Instruments BA II Plus - Page 128

122 BA II PLUS™ Calculator
Regressions
Formulas apply to all regression models using transformed
data.
()()()
()()
b
nxy y x
nx x
=
∑−∑∑
∑−∑
22
()
a
yb x
n
=
∑−∑
r
b
x
y
=
σ
σ
Interest Rate Conversions
EFF e
CY x
=× −
×+
100 1
1
()
()
/ln
where:
x
= .01
Q
NOM
P
C
à
Y
NOM C Y e
CY x
=× × −
÷×+
100 1
11
/
/ln
()
()
where:
x
= .01
Q
EFF
Percent Change
NEW OLD
CH
PD
=+






1
100
%
#
where:
OLD
= old value
NEW
= new value
%CH
= percent change
#PD
= number of periods
Profit Margin
Gross Profit Margin
Selling Price Cost
Selling Price
100
=
−
×