Sharp PC-1403

37
2. Two-variable Statis t ics and L i nea r R e gression
I n a d dit i on to the statistics f or bo th v ar i a b les x an d y which a r e t h e same as those of x i n
single - variable s tat i st i cs , t he sum of t he p roduc t s o f samp l es ~ xy i s obtained i n t wo -
va ri able statistics . Tw o -var i ab le s ta t i stics make po ssi b l e t he development of a relation-
ship ( c orrelation ) between t w o sets o f dat a . Each p a i r o f da ta ha s x and y values.
Fro m the s e s e t s of data a li ne of r egress i o n can be es t ab l i shed . T he r elationship of t he
two se t s of da t a b y use o f t he st r a i gh t li ne m eth o d is called Li n e ar R eg ression . I n Lin e ar
R egr e ssio n t her e a r e three i m p ortan t v a l ues , r , a , and b .
T he equ a tion of t he s tr a i g ht l ine is y = a + b x , w he r e a i s the point a t wh i ch the line
crosses the Y- axis and b is th e slope of t h e l in e .
T he correlation coe ff ici en t r s ho ws th e r e l a ti onsh i p b etween two se t s of data . A perfect
c o rrelatio n betw e en two va lu es i s a n r e qua l t o 1 ( - 1 is a pe rf ect negat i ve corr e la -
tio n ) ; i n other words , by kno w i n g th e va l ue of one va riab le you can predic t wit h 10 0%
accu r acy the va l ue of the ot h e r v a ri ab l e. T he furth er the v a l ue o f r is fro m 1 , the less
r e li ab le w ill yo u r predict i ons b e . T h e f o llow i n g t a bl e can be used as a set of defi n iti on s o f
the values of the corre l at i on coeff i c i e n t:
Di sp la y :
7 .
9 .
Key i n:
65 00 2 l s H tFT I ~
60 00 2 ffiilll
Correct Da t a ( C D): The l ast da t a en t ry i n t he above examp l e i s an e rr or a n d must be
ch a nged to 60 x 2 .
K ey i n:
Dis p lay:
M ean:
@!.Fil m
53 . 88888889
Stan da rd Deviation:
l sHIFT I ~
9 . 279607271
Var i anc e:
~
8 6.11 11 1 111
Not es: 1 . After a ll th e d at a ha ve b ee n e n tere d , s t atis t ics such as m ea n v a lue ,
s t and a rd d eviatio n , etc., may be ob ta ine d i n a n y de sir ed order .
2 . Aft e r a mean v a lue , st anda r d d e v iat io n , o r an y oth e r statis t i c ha s been
obtained a s a n i nter m e d i a te r esult, m or e data ca n b e ent e red and
statisti c al c a l cu lati o ns c a n b e p erf o rmed c on ti nuou s l y o n addit i onal data
entry .
Key in :
D i sp l a y
[ SH I FT I [ S TA T ]
0 .
35 ~
1 .
45
~
2 .
55 X 5
~
7 .
65 x 2
~
9.
A s each sample is entered , t h e n umber o f data o f that s amp l e will appea r at the right o f
the display.
Us i ng as a Calculator