View
246
Download
0
Category
Preview:
Citation preview
8/10/2019 SPSS Training Manual
1/50
SPSS
At the end of this session, you should be able to perform the following tasks
Introduction
The Statistical Package for the Social Sciences (SPSS) is a package of
programs for manipulating, analyzing, and presenting data; the package is
widely used in the social and eha!ioral sciences" The core program is called
SPSS #ase and there are a numer of add$on modules that e%tend the range
of data entry, statistical, or reporting capailities" &or e%ample, SPSS
'd!anced odels, SPSS egression odels, SPSS *%act Tests, SPSS Tales,
SPSS +ategories, SPSS Trends, SPSS issing alue 'nalysis etc"
Introduction to SPSS environment (Getting to know SPSS)
Starting SPSS
There are a numer of different ways to start SPSS-
. The simplest way is to look for an SPSS icon on your desktop" Place your cursor
on the icon and doule$click"
. /ou can also start SPSS y clicking on Start, mo!e your cursor up to Programs,
and then across to the list of programs a!ailale" o!e up or down until you find
SPSS for 0indows"
. SPSS will also start up if you doule$click on an SPSS data file listed in 0indows
*%plorer1these files ha!e a "sa! e%tension"
0hen you open SPSS you may encounter this grey front co!er screen asking 20hat
would you like to do34"
8/10/2019 SPSS Training Manual
2/50
5t is easier to close this screen (click on the cross in the top right$hand corner) and
get used to using the other SPSS menus" 0hen you close the opening screen you
will see a lank spreadsheet" To open an e%isting SPSS data file from this
8/10/2019 SPSS Training Manual
3/50
spreadsheet screen, click on File, and then Open, from the menu displayed at the
top of the screen"
pening an e!isting data "le
5f you wish to open an e%isting data file, click on &ile from the menu across the top
of the screen, and then choose 6pen, and then 7ata" The 6pen &ile dialogue o%
will allow you to search through the !arious directories on your computer to find
where your data file is stored" /ou should always open data files from the hard
dri!e of your computer, not from e%ternal memory dri!e"
Saving a data "les
0hen you first create a data file, or make changes to an e%isting one, you must
rememer to sa!e your data file" This does not happen automatically, as in some
word processing programs" 5f you don4t sa!e regularly, and there is a power
lackout or you accidentally press the wrong key, you will lose all of your work" So
sa!e yourself the heartache and sa!e regularly" To sa!e a file you are working on,
go to the File menu(top left$hand corner) and choose Save"
0hen you first sa!e a new data file, you will e asked to specify a name for the file
and to indicate a directory and a folder that it will e stored in" +hoose the directory
and then type in a file name" SPSS will automatically gi!e all data file names the
e%tension .sav" This is so that it can recognise it as an SPSS data file" 7on4t change
this e%tension, otherwise SPSS won4t e ale to find the file when you ask for it
again later"
Starting a new data file
Starting a new data file is easy in SPSS is easy" +lick on &ile, then, from the
dropdown menu, click on 8ew and then 7ata" &rom here you can start defining your
!ariales and entering your data"
SPSS windows
The main windows you will use in SPSS are the 7ata *ditor, the iewer, the Pi!ot
Tale *ditor, +hart *ditor and the Synta% *ditor"
8/10/2019 SPSS Training Manual
4/50
Data Editor window
The 7ata *ditor window displays the contents of your data file, and in this window
you can open, sa!e and close e%isting data files; create a new data file; enter data;
make changes to the e%isting data file; and run statistical analyses, the data editorwindow also contains the !ariale !iew
Viewer window
iewer window will open automatically when you open the data editor !iew,
This
window displays the results of the analyses you ha!e conducted, including tales
and charts" 5n this window you can modify the output, delete it, copy it, sa!e it, or
e!en transfer it into a 0ord document" 0hen you sa!e the output from SPSS
statistical analyses it is sa!ed in a separate file with a "spo e%tension, to distinguish
it from data files, which ha!e a "sa! e%tension"
The iewer screen consists of two parts" 6n the left is an outline or menu pane,
which gi!es you a full list of all the analyses you ha!e conducted" /ou can use this
side to 9uickly na!igate your way around your output (which can ecome !ery long,
!ery 9uickly)" :ust click on the section you want to mo!e to and it will appear on
the right$hand side of the screen" 6n the right$hand side of the iewer window are
the results of your analyses, which can include tales and charts (or graphs)"
Saving output
8/10/2019 SPSS Training Manual
5/50
To sa!e the results of your analyses you must ha!e the iewer window open on the
screen in front of you" +lick on &ile from the menu at the top of the screen" +lick on
Sa!e" +hoose the directory and folder you wish to sa!e your output in, and then
type in a file name that uni9uely identifies your output" +lick on Save"
NoteTo pre!ent confusion and frustration, get organized and keep good records of the
analyses you ha!e done and of where you ha!e sa!ed the results"
Printing output
/ou can use the menu pane (left$hand side) of the iewer window to select
particular sections of your results to print out" To do this you need to highlight the
sections that you want" +lick on the first section you want, hold the +trl key on your
keyoard down and then ust click on any other sections you want" To print these
sections, click on the &ile menu (from the top of your screen) and choose Print"
SPSS will ask whether you want to print your selected output or the whole output"
Pivot Table Editor window
The tales you see in the iewer window (which SPSS calls Pi!ot Tales) can emodified to suit your needs" To modify a tale you need to doule$click on it, which
takes you into what is known as the Pi!ot Tale *ditor" /ou can use this editor to
change the look of your tale, the size, the fonts used, the dimensions of the
columns1you can e!en swap the presentation of !ariales around from rows to
columns"
8/10/2019 SPSS Training Manual
6/50
Chart Editor window
0hen you ask SPSS to produce a histogram, ar graph or scatterplot, it initially
displays these in the iewer window" 5f you wish to make changes to the type or
presentation of the chart, you need to go into the +hart *ditor window y doule$clicking on your chart" 5n this window you can modify the appearance and format of
your graph, change the fonts, colours, patterns and line markers"
Snta! Editor window
The Synta% *ditor is particularly useful when you need to repeat a lot of analyses or
generate a numer of similar graphs" /ou can use the normal SPSS menus to set up
the asic commands of a particular statistical techni9ue and then 2paste4 these to
the Synta% *ditor (see &igure
8/10/2019 SPSS Training Manual
7/50
This is done in a dialogue o%" &or e%ample, when you ask SPSS to run &re9uencies
it will display a dialogue o% asking you to nominate which !ariales you want to
use"
&rom here, you will open a numer of additional su$dialogue o%es, where you will
e ale to specify which statistics you would like displayed, the charts that you
would like generated and the format the results will e presented in" 7ifferent
options are a!ailale, depending on the procedure or analysis to e performed, ut
the asic principles in using dialogues o%es are the same"
Sele"ting variables in a dialogue bo!
To indicate which !ariales you want to use, you need to highlight the selected
!ariales in the list pro!ided (y clicking on them), then click on the arrow utton
to mo!e them into the empty o% laeled ariale(s)" To remo!e a !ariale from
the o%, you ust re!erse the process" +lick on the !ariale in the ariale(s) o%
that you wish to remo!e, click on the arrow utton, and it shifts the !ariale ack
into the original list" /ou will notice the direction of the arrow utton changes,
depending on whether you are mo!ing !ariales into or out of the ariale(s) o%"
Dialogue bo! buttons
5n most dialogue o%es you will notice a numer of standard uttons (6>, Paste,
eset, +ancel and ?elp; see &igure
8/10/2019 SPSS Training Manual
8/50
. 6>- click on this utton when you ha!e selected your !ariales and are ready to
run the analysis or procedure"
. Paste- this utton is used to transfer the commands that SPSS has generated in
this dialogue o% to the Synta% *ditor (a description of which is presented earlier inthis chapter)" This is useful if you wish to repeat an analysis a numer of times, or
if you wish to make changes to the SPSS commands"
. eset- this utton is used to clear the dialogue o% of all the pre!ious commands
you might ha!e gi!en when you last used this particular statistical techni9ue or
procedure" 5t gi!es you a clean slate to perform a new analysis, with different
!ariales"
+ancel- clicking on this utton closes the dialogue o% and cancels all of the
commands you may ha!e gi!en in relation to that techni9ue or procedure"
. ?elp- click on this utton to otain information aout the techni9ue or procedure
you are aout to perform"
%losing SPSS
0hen you ha!e finished your SPSS session and wish to close the program down,
click on the &ile menu at the top left of the screen" +lick on *%it" SPSS will promptyou to sa!e your data file and a file that contains your output (results of the
analyses)" SPSS gi!es each file an e%tension to indicate the type of information that
it contains" ' data file will e gi!en a "sa! e%tension, while the output files will e
assigned a "spo e%tension"
%reating a data "le and entering data
8/10/2019 SPSS Training Manual
9/50
The asic steps in!ol!ed in the process of creating a data file and entering
the data using SPSS
A +heck and modify, where necessary, the options (or preferences, as
they were referred to in earlier !ersions of SPSS) that SPSS uses to
display the data and the output that is produced"
B Set up the structure of the data file y 2defining4 the !ariales"< *nter the data"
%hanging the SPSS &ptions'
The options allow you to define how your !ariales will e displayed, the size of
your charts, the type of tales that will e displayed in the output and many other
aspects of the program"
To open the 6ptions screen, click on Editfrom the menu at the top of the screen
and then choose Options"
8/10/2019 SPSS Training Manual
10/50
Tips
#d$ust as it suit ou. E!periment with different options at our own
"onvenien"e
$e"ning the variables
7efining the !ariales means informing SPSS aout your !ariale names and coding
instructions" /ou will do this in the Data Editor window, the 7ata *ditor window
consists of two different !iews- Data Viewand Variable View
Data Editor window
Variable View
/our o now is to define each of your !ariales y specifying the re9uired
information for each !ariale listed in your codeook" Some of the information you
will need to pro!ide yourself (e"g" name); other its are pro!ided automatically y
SPSS using default !alues" These default !alues can e changed if necessary"Values
5n the alues column you can define the meaning of the !alues you ha!e used to
code your !ariales" 5 will demonstrate this process for the !ariale 2Se%4"
A" +lick on the three dots on the right$hand side of the cell" This opens the alue
Cael dialogue o%"
8/10/2019 SPSS Training Manual
11/50
B" +lick in the o% marked alue" Type in A"
8/10/2019 SPSS Training Manual
12/50
Danger alert&&&
'hen entering data( remember to save our data file regularl. SPSS does
not automati"all save it for ou. )f ou don*t save it( ou ris+ losing all the
information ou have entered. To save( $ust "li"+ on the File menu and
"hoose Save or "li"+ on the i"on that loo+s li+e a "omputer dis+.
#odifying the data "le
'fter you ha!e created a data file you may need to make changes to it (e"g" to add,delete or mo!e !ariales; or to add or delete cases)" There are also situations
where you may need to sort a data file into a specific order, or to split your file to
analyse groups separately"
To delete a "ase
To insert a "ase between e!isting "ases
To delete a variable
To insert a variable between e!isting variables
To move an e!isting variable
To sort the data file
8/10/2019 SPSS Training Manual
13/50
/ou can ask SPSS to sort your data file according to !alues on one of your !ariales
(e"g" se%, age)" +lick on the 7ata menu, choose Sort +ases and specify which
!ariale will e used to sort y" To return your file to its original order, repeat the
process, asking SPSS to sort the file y 57"
To split the data file
Sometimes it is necessary to split your file and to repeat analyses for groups (e"g"
males and females) separately" Please note that this procedure does not physically
alter your file in any permanent manner" 5t is an option you can turn on and off as it
suits your purposes" The order in which the cases are displayed in the data file will
change, howe!er" /ou can return the data file to its original order (y 57) y using
the Sort +ases command descried ao!e"
Steps
A" ake sure you ha!e the 7ata *ditor window open on the screen"
B" +lick on the 7ata menu and choose the Split &ile option"
8/10/2019 SPSS Training Manual
14/50
&or some analyses you may wish to select a suset of your sample (e"g" only
males)"
A" ake sure you ha!e the 7ata *ditor window open on the screen"
B" +lick on the 7ata menu and choose the Select +ases option"
"
&or the analyses (e"g" correlation) that you perform after this select cases
procedure, only the group that you selected (e"g" males) will e included" 0hen you
ha!e finished the analyses, you need to go ack and turn the Select +ases option
off"
To turn the sele"t "ases option off
A" ake sure you ha!e the 7ata *ditor window open on the screen"
B" +lick on the 7ata menu and choose Select +ases option"
8/10/2019 SPSS Training Manual
15/50
7ata files can e prepared in the icrosoft *%cel program and then imported into
SPSS for analysis" 6ne word of warning- *%cel can cope with only B@E columns of
data (in SPSS language- !ariales)" 5f your data file is likely to e larger than this,
it is proaly easier to set it up in SPSS, rather con!ert from *%cel to SPSS later"
Step A- Set up the !ariale names
Note,The !ariale names must conform to the SPSS rules for naming !ariales
Step B- *nter the data
Step " The data will appear
on the screen with the !ariale names listed across the top" /ou will, howe!er, need
to go ahead and define the ariale laels, alue laels and the type of easure"
Step -, Saving as an SPSS file
0hen you ha!e completed this process of fully defining the !ariales, you need to
sa!e your file as an SPSS file" +hoose &ile, and then Sa!e 's from the menu at the
top of the screen" Type in a suitale file name" ake sure that the Sa!e as Type is
set at SPSS (H"sa!)" +lick on Sa!e" 0hen you wish to open this file later to analyse
your data using SPSS, make sure you choose the file that has a "sa! e%tension (not
your original *%cel file that has an "%ls e%tension)"
Screening and cleaning the data
#efore you start to analyse your data it is essential that you check your data set for
errors" 5t is !ery easy to make mistakes when entering data, and unfortunately
8/10/2019 SPSS Training Manual
16/50
some errors can completely mess up your analyses" &or e%ample, entering
8/10/2019 SPSS Training Manual
17/50
Step +* inding the error in the data "le
Pro"edures for identifing the "ase where an error has o""urred
ethod A
A" ake sure that the 7ata *ditor window is open and on the screen in front of you
with the data showing"
B" +lick on the !ariale name of the !ariale in which the error has occurred (e"g"
se%)"
8/10/2019 SPSS Training Manual
18/50
=" 5n the Cael cases section choose 57 from your !ariale list" This will gi!e you the
57 numer of the case, and will allow you to trace ack to the 9uestionnaireIrecord
with the mistake"
@" 5n the Statistics section choose 6utliers" To sa!e unnecessary output you mayalso like to remo!e the tick from 7escripti!es (ust click once)" +lick on +ontinue"
E" 5n the 6ptions section choose *%clude cases pairwise" +lick on +ontinue and then
6>"
Step -* %orrecting the error in the data "le
Pro"edure for "orre"ting the error in the data file
A" To correct the error, it will e necessary to go ack to your 9uestionnaires (or the
records from your e%periment)" &ind the 9uestionnaire or record with the 57
numer that was identified as an e%treme !alue" +heck what !alue should ha!e
een entered for that person (e"g" for se%- was it a male (score A) or a female
(score B)3)"
B" o!e down to the case numer that has the error" 6nce you ha!e found the
person with that case numer, mo!e across the row until you come to the column of
the !ariale with the error (e"g" Se%)" Place the cursor in the cell, make sure that itis highlighted and then ust type in the correct !alue"
This will replace the old incorrect !alue" Press one of the arrow keys and you will
see the correct !alue appear in the cell"
Note, 'fter you ha!e corrected your errors it is a good idea to repeat &re9uencies
to doule$check" Sometimes, in correcting one error, you will ha!e accidentally
caused another error" 'lthough this process is tedious it is !ery important that you
start with a clean, error$free data set" The success of your research depends on itJ
7on4t cut corners"
$escriptive statistics
7escripti!e statistics ha!e a numer of uses" These include-
8/10/2019 SPSS Training Manual
19/50
. To descrie the characteristics of your sample in the ethod section of your
report;
. To check your !ariales for any !iolation of the assumptions underlying the
statistical techni9ues that you will use to address your research 9uestions;and
. To address specific research 9uestions"
%ategorical variables
To otain descripti!e statistics for categorical !ariales you should use &re9uencies"
Procedure for otaining descripti!e statistics for categorical !ariales
A" &rom menu, #nale, then click on Des"riptive Statisti"s, then
Fre/uen"ies"
B" +hoose and highlight the categorical !ariales you are interested in (e"g"
se%)"o!e these into the ariales o%"
8/10/2019 SPSS Training Manual
20/50
Note on s+ewness and +urtosis
5nformation on skewness and kurtosis may e needed if these !ariales are to e
used in parametric statistical techni9ues (e"g" t$tests, analysis of !ariance)" The
skewness !alue pro!ides an indication of the symmetry of the distriution" >urtosis,on the other hand, pro!ides information aout the 2peakedness4 of the distriution"
5f the distriution is perfectly normal, you would otain a skewness and kurtosis
!alue of K (rather an uncommon occurrence in the social sciences)" Positi!e
skewness !alues indicate positi!e skew (scores clustered to the left at the low
!alues)" 8egati!e skewness !alues indicate a clustering of scores at the high end
(right$hand side of a graph)" Positi!e kurtosis !alues indicate that the distriution is
rather peaked (clustered in the centre), with long thin tails" >urtosis !alues elow K
indicate a distriution that is relati!ely flat (too many cases in the e%tremes)" 0ith
reasonaly large samples, skewness will not 2make a sustanti!e difference in the
analysis4 (Taachnick L &idell, BKKA, p" F=)" >urtosis can result in an underestimate
of the !ariance, ut this risk is also reduced with a large sample (BKKM cases- see
Taachnick L &idell, BKKA, p" F@)"
.sing graphs to describe and e!plore the data
/istograms
?istograms are used to display the distriution of a single continuous !ariale (e"g"
age, percei!ed stress scores)"
Pro"edure for "reating a histogram
A" &rom the menu at the top of the screen click on- Nraphs, then click on
?istogram"
B" +lick on your !ariale of interest and mo!e it into the ariale o%" This
should e a continuous !ariale (e"g" total percei!ed stress)"
8/10/2019 SPSS Training Manual
21/50
=" 5f you wish to gi!e your graph a title click on the Titles utton and type the
desired title in the o% (e"g" ?istogram of Percei!ed Stress scores)"
@" +lick on Continue, and then O0"
0ar graphs
#ar graphs can e simple or !ery comple%, depending on how many !ariales you
wish to include"
Procedure for creating a ar graph
A" &rom the menu at the top of the screen click on- Nraphs, then #ar"
B" +lick on +lustered"
8/10/2019 SPSS Training Manual
22/50
pro!ides a general indication of the strength of the relationship etween your two
!ariales"
Pro"edure for "reating a s"atterplot
A" &rom the menu at the top of the screen click on- Nraphs, then on Scatter"
B" +lick on Simple and then 7efine"
"
#anipulating the data
D#N2E3 #4E3T
ake sure you ha!e a second copy of your data set" 5f you make a mistake here
you will lose or corrupt your original data" Therefore, it is essential that you ha!e a
ackup copy" ememer that, unlike other spreadsheet programs (e"g" *%cel),
SPSS does not automatically recalculate !alues if you add e%tra cases or if you
make changes to any of the !alues in the data file" Therefore you should perform
8/10/2019 SPSS Training Manual
23/50
the procedures illustrated in this chapter only when you ha!e a complete (and
clean) data file
%alculating total scale scores
#efore you can perform statistical analyses on your data set you need to calculate
total scale scores for any scales used in your study" This in!ol!es two steps-
. Step A- re!ersing any negati!ely worded items
A" &rom the menu, click on- Transform, then click on ecode, then 5nto Same
ariales"
B" Select the items you want to re!erse (opB, op=, opE)" o!e these into the
ariales o%"
8/10/2019 SPSS Training Manual
24/50
. Step B- instructing SPSS to add together scores from all the items that make up
the suscale or scale"
A" &rom the menu at the top of the screen click on- Transform, then click on
+ompute"
B" 5n the Target !ariale o% type in the new name you wish to gi!e to the total
scale scores (it is useful to use a T prefi% to indicate total scores as this makes
them easier to find in the alphaetical list of !ariales when you are doing your
analyses)"
)mportant. ake sure you do not accidentally use a !ariale name that has
already een used in the data set" 5f you do, you will lose all the original data1
potential disaster; so check your codeook"
8/10/2019 SPSS Training Manual
25/50
details of what was done to "al"ulate it. )f an items were reversed( this
should be spe"ified along with details of whi"h items were added to "reate
the s"ore.
%ollapsing a continuous variable into groups
&or some analyses (e"g" 'nalysis of ariance) you may wish to di!ide the
sample into e9ual groups according to respondents4 scores on some !ariale
(e"g" to gi!e low, medium and high scoring groups)" isual #inning to
identify suitale cut$off points to reak the continuous !ariale age into
three appro%imately e9ual groups" The same techni9ue could e used to
create a 2median split4- that is, to di!ide the sample into two groups, using
the median as the cut$off point" 6nce the cut$off points are identified, isual#inning will create a new (additional) categorical !ariale that has only three
!alues, corresponding to the three age ranges chosen" This techni9ue lea!es
the original !ariale age, measured as a continuous !ariale, intact so that
you can use it for other analyses"
Procedure for collapsing a continuous !ariale into groups
A" Transform, and choose Visual 5inning"
B" Select the continuous !ariale that you want to use (e"g" age)" Transfer it
into the ariales to #and o%" +lick on the +ontinue utton"
8/10/2019 SPSS Training Manual
26/50
E" +lick on the ake Caels utton ack in the main dialogue o%" This will
automatically generate !alue laels for each of the new groups created"/ou
can modify these if you wish y clicking in the cells of the Nrid"
F" +lick on 6> and a new !ariale ('geand
8/10/2019 SPSS Training Manual
27/50
@" &or the second !alue 5 would type B in the 6ld alue, ut in the 8ew alue 5
would type A" This will recode all the !alues of oth A and B from the original coding
into one group in the new !ariale to e created with a !alue of A"
E" &or the third !alue of the original !ariale 5 would type A in the 6ld alue and Bin the 8ew alue" This is ust to keep the !alues in the new !ariale in se9uence"
+lick on 'dd" epeat for all the remaining !alues of the original !alues" 5n the tale
6ld8ew you should see the following codes for this e%ample- AA; BA;
8/10/2019 SPSS Training Manual
28/50
'e will be using the surve data "alled 6776 8.S. 2eneral So"ial Surve in
the installed SPSS.
?ypothesis
?o- There is no significant relationship etween le!el of educational 9ualification
and 6ccupational Prestige
?A- There is a significant relationship etween le!el of educational 9ualification
and 6ccupational Prestige
Preliminar analses for "orrelation
Pro"edure for "al"ulating Pearson produ"t9moment "orrelation
A" &rom the menu at the top of the screen click on- 'nalyze, then click on
+orrelate, then on #i!ariate"
B" Select your two !ariales and mo!e them into the o% marked ariales (e"g"
total percei!ed stress, total P+65SS)"/ou can list a whole range of !ariales here,
not ust two" 5n the resulting matri%, the correlation etween all possile pairs of
!ariales will e listed" This can e 9uite large if you list more than ust a few
!ariales"
8/10/2019 SPSS Training Manual
29/50
@" +lick 6>"
The output generated from this procedure is shown elow"
Highest Year of
School CompletedR's Occupational Prestige
Score (1980
Highest Year of School Completed Pearson Correlation 1 !"#0($$
Sig! (#%tailed !000
& 1"10 11"
Respondent's OccupationalPrestige Score (1980
Pearson Correlation!"#0($$ 1
Sig! (#%tailed !000
& 11" 118
$$ Correlation is significant at the 0!01 leel (#%tailed!
)nterpretation of output from "orrelation
A +hecking the information aout the sample (8)
B 7etermining the direction of the relationship ($!e or M!e)
< 7etermining the strength of the relationship (the !alue of r)
= +alculating the coefficient of determination
@ 'ssessing the significance le!el
Presenting the results from "orrelation
The results of the ao!e e%ample could e presented in a research report as
follows-
The relationship etween le!el of educational 9ualification (as measured y the
?ighest /ear of School +ompleted) and 6ccupational Prestige (as measured y the
espondentUs 6ccupational Prestige Score) was in!estigated using Pearson product$
moment correlation coefficient" There was a strong, negati!e correlation etween
the two !ariales VrD"@B, nDA=A@, pW"KKK@X, with high le!els of educational
9ualification associated with high le!els of 6ccupational Prestige"
Comparing the "orrelation "oeffi"ients for two groups
8/10/2019 SPSS Training Manual
30/50
Sometimes when doing correlational research you may want to compare the
strength of the correlation coefficients for two separate groups" &or e%ample, you
may want to look at the relationship etween educational 9ualification and
6ccupational Prestige for males and females separately"
Pro"edure for "omparing "orrelation "oeffi"ients for two groups of sub$e"ts
'- Split the sample
A" ake sure you ha!e the 7ata *ditor window open on the screen in front of you"
(5f you currently ha!e the iewer 0indow open, click on 0indow and choose the
SPSS 7ata *ditor")
B" &rom the menu at the top of the screen click on- 7ata, then click on Split &ile"
"
@" This will split the sample y se% and repeat any analyses that follow for these
two groups separately"
#- +orrelation
A" &ollow the steps in the earlier section of this chapter to re9uest the correlation
etween your two !ariales of interest (e"g" educational 9ualification, 6ccupational
Prestige)"
These will e reported separately for the two groups"
The output generated from this procedure is shown elow"
espondentUs Se%
?ighest /ear ofSchool
+ompleted
Us 6ccupationalPrestige Score
(AGK)
ale ?ighest /ear of School+ompleted
Pearson +orrelationA "==(HH)
Sig" (B$tailed) "KKK 8 E
8/10/2019 SPSS Training Manual
31/50
Us 6ccupational PrestigeScore (AGK)
Pearson +orrelation"==(HH) A
Sig" (B$tailed) "KKK
8 EA EBA
&emale ?ighest /ear of School+ompleted
Pearson +orrelationA "@=K(HH)
Sig" (B$tailed) "KKK
8 GFF FE
Us 6ccupational PrestigeScore (AGK)
Pearson +orrelation"@=K(HH) A
Sig" (B$tailed) "KKK
8 FE FF
$$ Correlation is significant at the 0!01 leel (#%tailed!
:Please remember, when you ha!e finished looking at males and females
separately you will need to turn the Split &ile option off" 5t stays in place until you
specifically turn it off" To do this, +lick on Data, Split Fileand click on the first
utton- #nale all "ases( do not "reate groups" +lick on O0"X
Partial "orrelation
Partial correlation is similar to Pearson product$moment correlation, e%cept that it
allows you to control for an additional !ariale" This is usually a !ariale that you
suspect might e influencing your two !ariales of interest" #y statistically
remo!ing the influence of this confounding !ariale, you can get a clearer and more
accurate indication of the relationship etween your two !ariales"
Details of e!ample
Procedure for partial correlation
A" &rom the menu at the top of the screen click on- 'nalyze, then click on
+orrelate, then on Partial"
B" +lick on the two continuous !ariales that you want to correlate (e"g" ?ighest
/ear of School +ompleted, 6ccupational Prestige score)" +lick on the arrow to mo!e
these into the ariales o%"
8/10/2019 SPSS Training Manual
32/50
"
+ontrol ariales
?ighest/ear ofSchool
+ompleted
Us6ccupationa
l PrestigeScore(AGK)
'ge ofespondent
$none$(a) ?ighest /ear ofSchool +ompleted
+orrelationA"KKK "@BK $"B@=
Significance (B$tailed) " "KKK "KKK df K A=A< A@KE Us 6ccupational
Prestige Score(AGK)
+orrelation"@BK A"KKK "KKF
Significance (B$tailed) "KKK " "F df A=A< K A=A=
'ge ofespondent +orrelation $"B@= "KKF A"KKK
Significance (B$tailed) "KKK "F " df A@KE A=A= K'ge ofespondent
?ighest /ear ofSchool +ompleted
+orrelationA"KKK "@
8/10/2019 SPSS Training Manual
33/50
+ompleted and 6ccupational Prestige), not controlling for your other !ariale" 5n
this case the correlation is "@BK" The word 2none4 in the left$hand column indicates
that no control !ariale is in operation"
B" The ottom half of the tale repeats the same set of correlation analyses, utthis time controlling for (taking out) the effects of your control !ariale (e"g" age)"
5n this case the new partial correlation is "@
8/10/2019 SPSS Training Manual
34/50
Some of the main types of research 9uestions that multiple regression can e used
to address are-
. ?ow well a set of !ariales is ale to predict a particular outcome;
. 0hich !ariale in a set of !ariales is the est predictor of an outcome; and
. 0hether a particular predictor !ariale is still ale to predict an outcome when the
effects of another !ariale are controlled for
%a$or tpes of multiple regression
A Standard multiple regression
B ?ierarchical multiple regression
< Stepwise multiple regression
#ssumptions of multiple regression
Details of e!ample
To illustrate the use of multiple regression we will e%amine the effect of 'ge of
espondent, ?ighest /ear of School +ompleted, ?ighest /ear School +ompleted$
father, ?ighest /ear School +ompleted$ other, ?ighest /ear School +ompleted$
Spouse on espondentUs 6ccupational Prestige"
?o- 'ge of espondent, ?ighest /ear of School +ompleted, ?ighest /ear School
+ompleted$ father, ?ighest /ear School +ompleted$ other and ?ighest /ear
School +ompleted$ Spouse will not significantly predict espondentUs
6ccupational Prestige"
?o- 'ge of espondent, ?ighest /ear of School +ompleted, ?ighest /ear School
+ompleted$ father, ?ighest /ear School +ompleted$ other and ?ighest /ear
School +ompleted$ Spouse will significantly predict espondentUs
6ccupational Prestige"
To e%plore this hypothesis, we will e using standard multiple regression
Standard multiple regression
8/10/2019 SPSS Training Manual
35/50
Procedure for standard multiple regression
A" 'nalyze, then click on egression, then on Cinear"
B" +lick on your continuous dependent !ariale (espondentUs 6ccupational Prestige
score and mo!e it into the 7ependent o%"
8/10/2019 SPSS Training Manual
36/50
(percei!ed stress) is e%plained y the model (which includes the !ariales of Total
astery and Total P+65SS)" 5n this case the !alue is "=EG" *%pressed as a
percentage (multiply y AKK, y shifting the decimal point two places to the right),
this means that our model (which includes astery and P+65SS) e%plains =E"G per
cent of the !ariance in percei!ed stress" /ou will notice that SPSS also pro!ides an
'dusted S9uare !alue in the output" 0hen a small sample is in!ol!ed, the
s9uare !alue in the sample tends to e a rather optimistic o!erestimation of the
true !alue in the population (see Taachnick L &idell, BKKA, p" A=F)" The 'dusted
s9uare statistic 2corrects4 this !alue to pro!ide a etter estimate of the true
population !alue" 5f you ha!e a small sample you may wish to consider reporting
this !alue, rather than the normal S9uare !alue"
To assess the statistical significance of the result it is necessary to look in the talelaelled '86'" This tests the null hypothesis that multiple in the population
e9uals K" The model in this e%ample reaches statistical significance (Sig D "KKK, this
really means pW"KKK@)"
ANOVA(b)
)odelSum ofS*uares df )ean S*uare Sig!
1 Regression #95.#!89# " "8.!".8 8!86 !000(a
Residual 6966.!5. "." 1#1!161
7otal 9900!5#9 "80
a Predictors/ (Constant Highest Year School Completed Spouse +ge of Respondent Highest Year SchoolCompleted ather Highest Year of School Completed Highest Year School Completed )other2 3ependent 4aria2le/ R's Occupational Prestige Score (1980
)odel
nstandardied Coefficients
Standardied
Coefficients t Sig!
9": Confidence;nteral for < Correlations
Collinearit=Statistics
"
The output generated from this procedure is shown elow"
This tale gi!es oth etween$groups and within$groups sums of s9uares, degrees
of freedom etc" /ou will recognise these from your statistics ooks" The main thing
you are interested in is the column marked Sig" 5f the Sig" !alue is less than or
e9ual to "K@ (e"g" "K
8/10/2019 SPSS Training Manual
47/50
The results of the one$way etween$groups analysis of !ariance with post$hoc tests
could e presented as follows-
' one$way etween$groups analysis of !ariance was conducted to e%plore the
impact of age on le!els of optimism, as measured y the Cife 6rientation test(C6T)" Suects were di!ided into three groups according to their age (Nroup A- B
or less; Nroup B-
8/10/2019 SPSS Training Manual
48/50
two !ariales- one independent !ariale (categorical) (e"g" Time AI Time BI Time
8/10/2019 SPSS Training Manual
49/50
%ultivariate tests
5n this tale the !alue that you are interested in is 'il+s* 4ambda, also the
associated proaility !alue gi!en in the column laelled Sig. 'll of the multi!ariate
tests yield the same result, ut the most commonly reported statistic is 0ilks4Camda" 5n this e%ample the !alue for 0ilks4 Camda is "B@, with a proaility !alue
of "KKK (which really means pW"KKK@)" The p !alue is less than "K@; therefore we
can conclude that there is a statistically significant effect for time" This suggests
that there was a change in confidence scores across the three different time
periods"
Presenting the results from one9wa repeated measures #NOV#
The results of a one$way repeated measures '86' could e presented as follows-
' one$way repeated measures '86' was conducted to compare scores on the
+onfidence in +oping with Statistics test at Time A (prior to the inter!ention), Time
B (following the inter!ention) and Time < (three$month follow$up)" The means and
standard de!iations are presented in Tale OO" There was a significant effect for
time V0ilks4 CamdaD"B@, &(B, BG)D=A"AF, pW"KKK@"
Two9wa between9groups #NOV#
Details of e!ample
)nterpretation of output from two9wa #NOV#
Presenting the results from two9wa #NOV##dditional analses if ou obtain a signifi"ant intera"tion effe"t
%i!ed between9within sub$e"ts analsis of varian"e
Details of e!ample
)nterpretation of output from mi!ed between9within #NOV#
Presenting the results from mi!ed between9within #NOV#
Non9parametri" statisti"s
Chi9s/uare
%ann9'hitne 8 Test
'il"o!on Signed 3an+ Test0rus+al9'allis Test
8/10/2019 SPSS Training Manual
50/50
Friedman Test
Spearman*s 3an+ Order Correlation
Recommended