SPSS Building a Basic Data Set
W
A L
D E
N U
N I
V E
R S
I T
Y
P
U B
H 6
0 3
2 /
8 0
3 2
S
P S
S R
E V
E A
L E
D
P
U B
H 6
0 3
3 /
8 0
3 3
I
N T
E R
P R
E T
A T
I O
N &
A P
P O
F D
A T
A
T yp
es of V ariables &
L
evels of M easu
rem en
t
T yp
es of V ariables
y A
variable is an y factor, trait, con
d ition
, or d isease
th at exists in
d ifferin
g am ou
n ts or typ
es. y
E xp
erim en
tal an d
observation al stu
d ies con
sist of several typ
es of variables. y
A ll stu
d ies in
volve at least on e in
d ep
en d
en t variable
(IV ) an
d on
e d ep
en d
en t variable (D
V ).
{
G et acqu
ain ted
w ith
id en
tifyin g th
e IV an
d D
V . It’s th
e first step
in d
evelop in
g a research qu
estion .
D ep
en d
en t V
ariable (D V
)
y D
isease or h ealth
ou tcom
e of in terest
y P
resu m
ed effect of a stu
d y
y Syn
on ym
s: O u
tcom e or C
riterion variable
y E
xam p
les: {
C an
cer {
D iabetes
{ H
IV statu
s {
C H
D m
ortality {
D en
gu e in
fection
In d
ep en
d en
t V ariable (IV
)
y P
red ictor or exp
osu re of in
terest y
P resu
m ed
cau se of a stu
d y
y Syn
on ym
s: E xp
erim en
tal, P red
ictor, or M an
ip u
lated
variable y
E xam
p les:
{ A
ge {
R ace
{ In
com e
{ B
M I
{ D
ru g U
se {
C on
d om
U se
C on
fou n
d in
g V ariable
y A
variable th at obscu
res th e effects betw
een th
e IV
an d
D V
y
A variable th
at th e research
er failed to con
trol or elim
in ate
y Syn
on ym
s: C ovariate, T
h ird
variable, M ed
iatin g
variable y
E xam
p les:
{ C
igarette sm okin
g con fou
n d
s th e effect betw
een d
rin kin
g coffee (IV
) an d
h eart d
isease (D V
) {
D iet, age, an
d gen
d er con
fou n
d th
e effect betw een
lack of exercise (IV
) an d
w eigh
t gain (D
V )
L evels of M
easu rem
en t
y E
ach variable can
be classified by its level of
m easu
rem en
t. y
W e w
ill classify accord in
g to term s u
sed in
th e
G erstm
an (20
16 ) textbook. H
ere th ey are listed
in
ord er of in
creasin g p
recision :
{ C
ategorical {
O rd
in al
{ Q
u an
titative
{ It is im
p ortan
t to u n
d erstan
d th
e d ifferen
t levels of m
easu rem
en t as th
ey h elp
d eterm
in e th
e statistical test th at
sh ou
ld be carried
ou t.
C ategorical
y C
lassify observation s in
to n am
ed categories, w
ith n
o in
trin sic ord
erin g of th
e categories y
C ategories are often
assign ed
n u
m erical valu
es as labels (eg., 0
= N
o, 1= Y
es) y
Syn on
ym s: N
om in
al y
C ategorical variables w
ith 2 levels are also called
B
in ary or D
ich otom
ou s
y E
xam p
les: {
G en
d er: M
ale/F em
ale {
R ace: B
lack/W h
ite/O th
er {
M ortality statu
s: D ead
/A live
O rd
in al
y C
ategories th at can
be p u
t in ran
k ord er
y E
xam p
les: {
Stage of can cer (I, II, III, IV
) {
Sm okin
g frequ en
cy (n on
-sm oker, ligh
t sm oker, m
od erate
sm oker, h
eavy sm oker)
{ Y
ear in college (fresh
m an
, sop h
om ore, ju
n ior, sen
ior)
Q u
an titative
y T
ru e n
u m
erical valu es th
at can be p
u t on
a n u
m ber
lin e
y Syn
on ym
s: C on
tin u
ou s, Scale, an
d In
terval y
E xam
p les:
{ A
ge (years) {
B M
I (kg/m 3)
{ Seru
m ch
olesterol (m g/d
L )