40    SPSS FOR SOCIAL SCIENTISTS
Sav0 r, |   i 5PSSM«m:BO0K
Figuro 15c    Save Dal» dialog box
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Be caiďul lítat the version of Hip dala file you save is the version you w.ml to W F« instance, a common mblakc students make b lo select a subset of cases (say. only the males in Ihe sample) and then save the dataflk Inter or. withoul turning off Ihe selection. The next lime Ihey come lo analyse Ihe dala hic. Ihey discover lo their constern.ilion th.»l only the selected cases arc tcftt A 'safely net' is to save your later vcmon under a slightly different file name-, for example, Vtr§2. Then, If you realise yon have made a mistake, you cm always go hack and resurrect Ihr earlier version of the dala file: versi.
Labelling variables
An SPSS data file requires both the d.i!.i and information about lbe variables. Tllť dala is visible in the Dala View window, and lite information about Ihe variables i$ visible in Ihe Variable
View window of the Data Kditor.
When the SPSS Data Kditor is in Data View format, each column in Ihe «ml represents a wrrinWr. SPSS requires each that each variable must have a unique name' that idenlili« thai variable separately from *ny other variable. These v.iu-ible names should be intelligible and adhere to the SPSS rules (or naming variables. - SPSS requires that variable names should be short words (limited I" a maximum of eight chancier«). II is good practice for Ihese variable labels to be one of three types.
•  Sfíŕ-ripWrvy labels staling what Infoimation the variable signifies (for example, sex,
•  An «Wtrj» that helps jog the researcher's memory about what the variable b (for example, hoh foi   Head Of Household/ or denom for a reifem» denominahon coding)
•  |ust I list of letter* mid inuirben in «v)/'»'« (for example. Vi. VI, V3, VI.... Vh)
Which is besl depends largely upon personal preference and convenience. Some researchers use Ihe question numbers as variable names, for example, quel a» a variable name for the first question In a survey.
DATA INPUT    41
ThVrV ■"«' some conventions thai must be followed when assigning variable names.
« A variable name must begin with a letter (not a number)
9   \ verüble name cannot have a Mure sjaior within the name (for example dog day would
,„,[ bfl acceptable bill dog_dny would be acceptable) »   \ triable name cannot be more llian řiy/ií rnonttftTf (a character is a letter, number or the
lymbob («. #. w or $t e A vaiiable name Cannot have Ihe special tlutMi'lm 1,1 and * or other special characters
, -, ept those listed in the previous bullet potnt
•  a variable name Cannot be our of ihe words SPSS uses as icynwife (for example, AND, NOT, EG BY and ALL)
•  A variable
nan ■ cannot end wilh a fitll stop.
Coding
The data that one wishes lo put into a computer package for analysis has to be transformed Írom ili completely non-computerised form (which could be answers written onto a questionnaire, entries on a form or application, a personnel or student record flic, etc.) into a shape lhal can be input into a computer. Usually, this means thai the intorm.ition is converted into number values - a process called loding. Coding operations con be carried out in several ways depending on Ihe type of information you are dealing with There are two types of data - iji-Niliiiifier and lyuilihttive
Qiitmlilutive aula
Kibe informal ion is already in number form, the coding is faidy simple; just Ihe liiml transfer of the numeric value. Foi instance, on the 'Drinking questionnaire'. Robert b 45 years old, Ihe ."•■.' ■ ■ •>,'.• is '.;:np'\ 45 Sir-il.nly, the OOCaN !<>:.'. is n: ;■.. i .ľ! cen ]','■>■•' I of WÍM and measures of spiril» are all coded dlicctly on the 'Drinking questionnaire'.
Numbers with decimal points can be coded wilh or without the decimal point. For instance. Fred answered on the "Drinking qucslionnaire' that he spent £4,55 on alcohol lasl weekend This could be coded as 4.55 or 0455 (the first case is Ihe version of coding we ore using with the qucslionnaire). Ihe default for SPSS is eight digits with two places lo the right of the decimal point. If more digils or decimal places are required this can be changed in Ihe Variable View window of the Data Editor (which is explained below;
These days, thanks In the power of modem computers and Ihe ability to manipulate datu after input into SPSS, one should always code in the most detail practicable. When coding numbers, this means that the number is the code - you lhnuld not amalgamate the »umlier values together Into larger categories al the coding stage. The reason for this is thai, if Ihe values are lumped together before input into SPSS, it will be impossible to get back to the detailed infoc-mation of the real number That is, you have unnecessarily thrown away some infoimation that could prove vital al some future dale. As you will see when you look at data manipulation «n Module 3. it b a simple matter lo aggregate numbers logclhei after data ha» been input into SPSS.
42    SPSS FOR SOCIAL SCIENTISTS
For instance, as an example of kul coding procedure, some people would have coded people'* ages on Hie 'Drinking questionnaire' ihmlh/ intu allegories.
Ung*f Hmn 1ft 2-18 to 24 J - 23 In 40 4     u to '-i
We would advise thai you avoid premalurely categorising quantitative data Mich a* tlicir. Wli.il if, later on. you discover lhal you really need to compare Ihc drinking habits of those aged les* than 21 with those aged between II and 297 II will be impossible becnuse your age categories will not allow it. (f you had coded age dlreclly. you could easily amalgamate up Into
i • i;ories required for your analysis. It is always possible to move from a ii«'i.       \ \ coding to a less detailed coding: the reverse cannot be done* (If you are familiar with scaling or level* of measurement, you may have noted that so fa* we have been talking About the ijiKinMiifiiv levels of measurement: interval and ratio scales. Levels of measurement   /.ill bfl diwiiwd in more detail at the beginning of Module 2).
QuflUtfítlv* data
Quite often, the information you want to code may not be number values, bul instead in the form of MftgariB
•   1 hetc can be mutually citli&ivt, binary Hack Of white" calegoncs where one category iinjilies the absence or opposile of the oilier, fur example. YES or NO
or (from the 'Drinking quciHoiltUlnV) I ■ Mire, 2 =* t'tmalc
•  Thoi c can also be more fluni fivo categories ■ a set of categories where each in .i different lypc of a common characteristic:
for example. Car Colours: BLACK/MIX BLUE/CRF.EN/YELLOW, etc.
Of Ifiom the 'Drinking questionnaire'/
Faculty: Social Scicxes ~ I; Ar h — L Seimte— J; íitginetriry=4; Olhrr — 5
I |eic. of course, Ihe number codes are only labels fur the categories and du not havo any arithmetic value in themselves (for example, tngiiuering, coded %'. is not twice as much a faculty such as Arts, coded '2'f>. These suits of calegorial data can be described as being at lhe nonU'uil level of measurement
There is an in-between situation where you can have categories that fall into *n imrerornjt of rfrrr*wur order. The number codes used to represent the categories show Ihe ordering effect but do no! literally represent a true amount ui quantity. For instance, people could be asked lo rank I sensation by ils pain:
liikles/uncom/otlable/hurls/lmrls n lat/ncmmUngllf 12              3          4                 5
We could agree that omy Ukteť (1) Is less pain than 'uteomjoriabk' {21 winch Is less pain than fcenV (J) and so on (l< 2 < 3 < 4 < il but we would probably find ä hard lo agree that Ihre* 1'iilts and an 'iwrairn/mrrtWe* equals ono 'axmriuimg!/? (l-f-I + l+2«5)l
DATA INPUT    43
ibe 'Pr'"'lio*t q'Mrstionnaire' liiere is an example of Ihi» sort of ordinal measurement .iT . |K' numbers imply * decreasing or increasing order, but the numbers themselves signify 1   I   k-* ,,r n'onf •""* wt *"* <*e"n',e amounts:
Do V»"
! 0 ■jvpttv »Vfiift rtfal/wf", 2 - 'Drink rstre/y", 3 = 'Drink inodtnittly', i = 'Prink freifiitnUy'. 5 - Witt lienvily'l
The «»»«»I and ordinal levels of measurement will be discussed in more detail at the beginning of Module 11
'Siring  dala
VVIiilc numbers art......Hilly used to record information, it is possible lo enter in letters - or,
pun et*Ctly< «'(''"'«»»""c nv/rs For instance, there could be goo<f reasons to enter in people's own names; we have done trus on the "Drinking questionnaire' with Ihe variable name which has respondents* names Sometimes an interview schedule may contain 'open-ended" Questions ivhcre you might waist to record exactly what a person said in response lo a question otrbalim instead of converting what Ihey said into a number code.
These alphanumeric codes are called sfnne variables (technically, they are In 'A' format). Even if lhe codes of a variable dedaied as a string variable arc numbers, they cannot have arithmetic opcrolicns performed on them as normal number-based codes unless Ihey »re specially altered.
Alphanumeric codes are fairly rare, especially in datasets designed for statistical analysis. They arc more common in datasets which originate from a per40nnd file or the like. They have been mentioned here since you may encounter them. 1ml we recommend that you avoid wiling up variable) as string variable if possible.
An impoilanl note! SPSS will permit alphanumeric code» (for example, words such as respondents' names) lo he entered inlo Ihe Data View window only II the variable has been defined as a šíril« voriuble. To change the variable type, switch to lbe Variable View format of the Data Edilor. Click on the Type cell of the variable you wish to ch.ingf. arid alter the setting to String. (The us« of Variable View is covered in detail brlow in the section on SPSS operations to 'label' and 'refine' a dataset.)
Refining the data set
At this point after lbe dala has been coded and input into SI'SS. you could, in theory, move straight into a statistical analysis of some sort. In practice, however, the basic dalaset is usually 'refined- before we can consider it to be completely ready for analysis. This 'refining' can consist of three types of opeialionv
Attaching special descriptions or labels that help explain tbc !•>•'•' and (anient of the
da laset
Carrying out wlJnhnn or wnusteiicy checks to remove or control errors and missing
information in lite dataset
Tagging rni>sniv o' utrWií atlti with specia I Libels so that these incorrect codes aren't
mixed in wilh valid v.ikics when analyses are being carried oul
m   m";k f oh social sciľmtim:;
Attache« wedal docripHowac Ubtb Ihat Kilp iiaMn Ihe form and content »t lltc n Mnllal Whee il makes no different e lo ihe adual numerical analyses. ■' li ■ '■■-■■ i ■ document 11« structure •>* .1 ihi.i-.H and u. mi.»U .!■-..npiions of the meanings of variable nam« .»»I the codes of ihr variable» All «»I Ihli may .rem clem and straightforward, lo you Ihe DSnon who sel up the datMCt - Uli iMl mlghl not be Ihc case (■» someone ehe who will h|V1   |p try «id analyse the dala .il some fulUN dilti Also, features of the data thai seem il r aighl forward lo you fodny. might not be w obvious or straightforward lo you eone menns Wrr. Consequently. SPSS allow» you to 'document' a datasct as you set it up   i 1 mallon on each of the variables is presented in lbe Variable View window of the Data I dllOr
Varíabk labtk
A iuthin.ni («ature for docaatanUng i dataael n .1 provision that allows one in attach 1 'descriptor' or 'label' to the short vaň                        't|r variable names an                     lo einhi
iUn.Mtei% which may be obscure and ruquie darination For Instance In Ihe
It» r« 1    1 variable timed fa    rrhfch may W rather vague to someone not bfllRW with the dataiet. But If * dese^ceVlabd ta aJlaehed    for example, fee    fetum/ril
arroHtgt ■ the meaninij of the variable be.......n......ch more dear. Theta detothi can be entered
In column liibul in the Variable View window,
Vah* hMs
A Umilar problem exists for the Individual codea of a variable. Again, a common fa 1 1 1 ■ . 1 many data analysis packages is a provision Im attaching a 'descriptor* 01 label lo Indlvtdual codes ľ"i Instance, the variable sac haa ilx codes    1. 2, 3. 4. 5 and 9    ih,ii in. wild 11 it
would be ea>,y to forget what these nix r'inten mean, »»t, If descriptors/label', .ire attached, tlrlll meanlngi are much clearer:
i           otuittxrs, i = /V                                • ■  iwrrme.
■.     . »titer. 9 = N.«f dí-p/ícnWr
......   .1 variable and its values »re labelled', these descriptors will appear Ofl «iy | <■ ■
When Ihe variable name or lbe numbtl Codtl Would appear. For instance, wilhout U li | lobulation of fac for 500 cases could louk like thlst
'.■'■>" >■'!■      '■»
1	57
7	IM
:i	-1,!
'■	IC
u	4
11	23
row	ÜO0
Unless one was very familiar with Ih                   Ms would be completely obwuir Now, with
(lie descriptors, we obtain a much less vague tabulation:
HA IA INPUT   45
'/•rtab '■     fac. Faculty
1 SoeM.....■- -"•	'•:
7 AM	1«
3  fiCMHKO	N
!   1 ,   .,.',■■  '..'•.;	p.'
5  OfrW	4
I) Not /iwlicable	;■"
total
'.:»;
|k« kbets do not alter the mathematical calculations: of Ihc programme in any way. The ertxvt they it> Iwve is lo make Ihe printout much easier to understand
SPSS optrattoiti to 'label' una 'růflnť « datasůl
\\m\ lei u' K'« through il»' operation)  equired lo fully label new varlablei.....SPSS dala file.
lime are a numoei of ways lo  it up variable tabel; and valu                                         o»edures
ir-nig SľSS Vio .»«• *lic.Uly «bffenml to older versions of SPSS - tee Appendix Z p:56, for
example.....
As already deKflwd, Ihr Variable View lornvM of the IJal.i BdHlOt        1      "ils of each of
tbe variables whoM values an entered m Data View formal While »i tl lechnleally possible to
cnmpkte soiup sl.ilbitlenl proieil.....:; without details of ÍÍCh of Ihc varlablea.il Ifigood practice
for the SPSS user to supply ami Complete the VaH„blc View detailu To change to Variable View tormat, click on tlie lab labelled Variable View at Ihe bottom of the left-hand side of the Pata Edilor window (figure 1.4a), Notice how the grkl switch« when you do this.
I I).....1 1 4«    Oponiny Variable Vlow in ll>» I )|itn ľ illti
11 'ľ jmu  11111  WEmmmmmmaamtam
E<a tut y>w y*«    ......               ,1     11b« w«u u*
■    '-'    'I "-I "I     1 :    I 1 »««*»
^MJrJíalÄl^iall
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To open Variable View window dick on the label on tl»o tKitlom lolt-h.iml skla of the Data Vlow wniilow In II») Dilta üditor.
rhcn>u> Invariable View rormal contauidelalbofeach variable I   ■                  ih ihe variable
name (Figure 1 4b). liach n*rWiM provides specific mformalion about Ihe variables. For example lbe Names of the variables are presented in the first column. Type ol eath variable is in Ihc
40    SPSS FOR SOCIAL SCIENTISTS —I----------------------------------------------------------------
wconJ column, <u   E» h rare pruvldci »pectu h formation ol cadi variable, includlup. Name.
ľype of variable.  VViillli. !).■.....,iln   I iln-k   Value*   nils.....i
f lyur« 14b    Variable View vr»i*»ow of It* IXilii I .»tor
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specific niM< i.. . n variable, o.fj lil in numeric. Is »non «.iLvadors wd«. hm im decimal points
F i«* ti cefvtmi provtdea specific information about tho variable?, cg. ti.uii" d Bavit v ir.iW«, Type oí «och variable, etc.
Unlll changed by Iht iMcr. Variable View foi.....I pre «ftla tlu- default iipecis <>f Ihfl variable.
Pot «ample. oj.Ii «..ii.il>lť will líc Typ« Numeric' wllh« Width of '$' character!, V dedrnaU,
no tpecibed   label* « mi5«nj( data,  etc   Any of  ll-'ie chaf» lOftollM  ..n  be chained  m  lbe
i lita Editor window when it n m Variable view formel (Figura i 4c)
Figure I Ac    E<llt(no/changliig the Variable View window of (li* Data Editor
I I. I    •]■. ..| I'm ..H     'M.'   ,:!''.■ i     I'l I •-   ■ |..iri,;(.tj
by cocking on lit« cc*, then clicking on tl<e
iMi/hhyhlod OOflW ol Iho colt.
.'i.   .'i
Typo     | WhIIIi   Decimal               I ah*t
, Numeric__
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n             Mľiililii iiionnumboriNono
M            'Řai.(towfenl nam«      Hoi I
D             Sei "i ■■' pondanl     Nona
"7jj„.......... „ j
[SPSS CiotMi« iim.vSy
V,iil,ihlp nainon can bo changed by rypeig ove/ It» dufautt names
OATA INPUT    47
(>i ílu- «li-f.iirll ehara» lernt»* will br appropriate for cad» vanal4ľ. but some may need lo
j    .-temniti, ľ ,s quit* ť,l%V i° change a i bar» leiWi   by dtdiMig on the cell containing 'hr1
,i,.inuiii>" '"' example, iliľ v.in.iblľ id i% numeric, but II»' variable name li .i plrfuf (person'«
,,. uiIki Hun manbcfl  l<» change the Type move the curecM to Hw Ihre« doli m ihr
J, Hlť J 1......1   "I  Ih« ľ'H Iňd  dkl  <nur    nib  will  opru Iha  nbwindOH   Wllh  "iř;!il  vaiublr
. .    i   Pqjurv i ad, CUcV on 'llrlng' vorlibl« .»"i chango tl»' width in 10 el.....icleri i»
A11-nnwdjle long«, namci
I i»|iin>  1 4(1
<*•*! Vaiialilp Typ«
Va*'d!iM Ivi"'
C jjumoiic
r [juj
r ScinnUe notation
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Cancel
CbMaolcit     ID
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.
Qa:k on Hm Siring v.iil.iliht.
ľ , —i , ih., IMOtftQftfw
chmncieis from 8 lo o number which suits your vnriabl«.
SPSS given ■"■ Ihc fatilily m Variable View h» inclodinj; lullri details lot oadi variable Ráme
by otladiiiif; a longer label lo it For example, w might want lu give the v.wi.ibV name wrnd Ifoi Ihn ipii'slion in lhe lUrvoy t>id won driiil Uisl wťľkŕiul Invlmrni 12 noOH PII rVMny umí Ins! Sidoitty WieíříV a longei label lo help 11* reuM'tnbcr wli.il iveiid is. To iíiív/ líir ixírínl'/ľ Haut, amply type in Ihc lull labd in lbe cell ol that variable. For example, lo give more details to the variahlu nnmo wend, move llic cursor nlonj; Ihc row contolnin,; wend until you reach the Umn Click on llm «'II. and type in |lu> Full detail«, n shown in Figur« 1.4c. i. i .i■ -1 ii l.í'il to LiM tii'U ff llit nwnlvi imfrt for catcgomal vjn.ibka. Tndotu. dickon ihc .ell nl tin? VATlflblc you wldi lo dtfinc. Movi« Ihc cursor to lh< three dots m |hfl ihoded (oilier >il ílu- tell .uul click oiue   Hi» will t'| '                   g box wlmh nllows you to l.ibi-1 each of tin'
values, auch .1% lhal in PlOUnl I 4(. In the example here, for the variable fac tfmiliy), 1 = 'Social
Sciencii', .'.    Ails', .1 ■  Siii'iiM-.'. 'i    'Bngliviurlng' and 9    '< llhoť. in tl»' dialog box for tin*
nl   I     lyp* HI tlie lit'l Minbci axle (wlmli i*  I) in Hie  Value box. ihen 'Id   on ll"' Vilue
MMrlbim and lypc In Iho labii fen nSecodt (which b Social SkbtnceX Okk on !!»• Add button, and the value .»»I its label nre entered Into Iho workbox. Ur|M-ni ibis foi each value, and thro diet on OK lo nvctha lalieU
flu longer labels attjiheil lo the shml variable name ■" to Ih« number eodrl ní v■   i have no i'ffeil whateVOI Oil any analysis tllOl SPSS will cany oul   Whal the Iflbvll do i^ mill"' Ihc output moiling from an analysis cut v lo wrřrrp/rí. Onrr ll»e variables have l>een lalielled i;r*jS aulunwHcarly will pnul lbe longer labeh next lo variable names and vakies wherever HK'kC appeal on the outprlnl. making the output much culei for you lo read an<| understand