Scoring Definitions

Template

Master Scoring Summary

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38 44 52 44 60 38 50 50 52 48 48 48 50 52 58 42 58 54 54 54 50 46 58 22 14 28 10 18 28 12 12 28 26 22 22 28 28 26 24 28 28 28 28 26 26 28 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Economic Fit/Attractiveness

Ability to Execute/Business Fit

TIM-7101_Video_Game_Data

Evidence?Based?Library?and?Information?Practice?2007,?2:1?

32

Evidence?Based?Library?and?Information?Practice
?

?
Feature?Article?
?
A?Statistical?Primer:?Understanding?Descriptive?and?Inferential?Statistics?
?
?
Gillian?Byrne?
Information?Services?Librarian?
Queen?Elizabeth?II?Library?
Memorial?University?of?Newfoundland?
St.?John?s,?NL?,?Canada?
Email:?[email?protected]?
?
?
Received:?13?December?2006? ? Accepted:?08?February?2007?
?
?
??2007?Byrne.?This?is?an?Open?Access?article?distributed?under?the?terms?of?the?Creative?Commons?
Attribution?License?(http://creativecommons.org/licenses/by/2.0),?which?permits?unrestricted?use,?
distribution,?and?reproduction?in?any?medium,?provided?the?original?work?is?properly?cited.?
?

Abstract?
?
As?libraries?and?librarians?move?more?towards?evidence-based?decision?making,?the?data?
being?generated?in?libraries?is?growing.?Understanding?the?basics?of?statistical?analysis?is?
crucial?for?evidence-based?practice?(EBP),?in?order?to?correctly?design?and?analyze?research?
as?well?as?to?evaluate?the?research?of?others.?This?article?covers?the?fundamentals?of?
descriptive?and?inferential?statistics,?from?hypothesis?construction?to?sampling?to?common?
statistical?techniques?including?chi-square,?correlation,?and?analysis?of?variance?(ANOVA).?
?

?

Introduction?
Much?of?the?research?done?by?librarians,?
from?bibliometrics?to?surveys?to?usability?
testing,?requires?the?measurement?of?certain?
factors.??This?measurement?results?in?
numbers,?or?data,?being?collected,?which?
must?then?be?analyzed?using?quantitative?
research?methods.?A?basic?understanding?of?
statistical?techniques?is?essential?to?properly?
designing?research,?as?well?as?accurately?
evaluating?the?research?of?others.??

This?paper?will?introduce?basic?statistical?
principles,?such?as?hypothesis?construction?
and?sampling,?as?well?as?descriptive?and?
inferential?statistical?techniques.?Descriptive?
statistics?describe,?or?summarize,?data,?while?
inferential?statistics?use?methods?to?infer?
conclusions?about?a?population?from?a?
sample.?
?
In?order?to?illustrate?the?techniques?being?

Evidence?Based?Library?and?Information?Practice?2007,?2:1?

33

? ? ? ? ? ? ???Great?Job? ? ? ???Lousy?Job?
? ? ? ? ? ? ? ? ? ? ? ? ?
If?you?accept?the?job? ? Have?a?great?experience? Waste?time?&?effort?

?
If?you?decline?the?job? Waste?an?opportunity? Avoid?wasting?time?&?effort?

?
?
Figure?1.?Illustration?of?Type?I?&?II?errors.?
?
?
described?here,?an?example?of?a?fictional?
article?will?be?used.??Entitled?Perceptions?of?
Evidence-Based?Practice:?A?Survey?of?Canadian?
Librarians,?this?article?uses?various?
quantitative?methods?to?determine?how?
Canadian?librarians?feel?about?Evidence-
based?Practice?(EBP).??It?is?important?to?note?
that?this?article,?and?the?statistics?derived?
from?it,?is?entirely?fictional.??
?
Hypothesis?
Hypotheses?can?be?defined?as??untested?
statements?that?specify?a?relationship?
between?two?or?more?variables??(Nardi?36).?
In?social?sciences?research,?hypotheses?are?
often?phrased?as?research?questions.?In?plain?
language,?hypotheses?are?statements?of?
what?you?want?to?prove?(or?disprove)?in?
your?study.??Many?hypotheses?can?be?
constructed?for?a?single?research?study,?as?
you?can?see?from?the?example?in?Fig.?1.?
?
In?research,?two?hypotheses?are?constructed?
for?each?research?question.?The?first?is?the?
null?hypothesis.??The?null?hypothesis?
(represented?as?H0)?assumes?no?relationship?
between?variables;?thus?it?is?usually?phrased?
as??this?has?no?affect?on?this?.??The?
alternative?hypothesis?(represented?as?H1)?is?
simply?stating?the?opposite,?that??this?has?an?
affect?on?this.??The?null?hypothesis?is?
generally?the?one?constructed?for?scientific?
research.?
?
Type?I?&?II?Errors?
Anytime?you?make?a?decision?in?life,?there?is?
a?possibility?of?two?things?going?wrong.??
Take?the?example?of?a?job?offer.?If?you?

decide?to?take?the?job?and?it?turned?out?to?be?
lousy,?you?would?have?wasted?a?lot?of?time?
and?energy.?However,?if?you?decided?to?pass?
on?the?job?and?it?was?great,?you?would?have?
wasted?an?opportunity.??It?s?best?illustrated?
by?a?two?by?two?box?(Fig.?1).?
?
?It?is?obvious?that,?despite?thorough?research?
about?the?position?(speaking?to?people?that?
work?there,?interview?process,?etc.),?it?is?
possible?to?come?to?the?wrong?conclusion?
about?the?job.??The?same?possibility?occurs?in?
research.?If?your?research?concludes?that?
there?is?a?relationship?between?variables?
when?in?fact?there?is?no?relationship?(i.e.,?
you?ve?incorrectly?assumed?the?alterative?
hypothesis?is?proven),?this?is?a?Type?I?error.?
If?your?research?concludes?that?there?is?no?
relationship?between?the?variables?when?in?
fact?there?is?(i.e.,?you?ve?incorrectly?assumed?
the?null?hypothesis?is?proven),?this?is?a?Type??
II?error.?Another?way?to?think?of?Type?I?&?II?
errors?is?as?false?positives?and?false?
negatives.?Type?I?error?is?a?false?positive,?
like?concluding?the?job?is?great?when?it?s?
lousy.??A?Type?II?error?is?a?false?negative;?
concluding?the?job?is?lousy?when?it?s?great.??
?
Type?I?errors?are?considered?by?researchers?
to?be?more?dangerous.??This?is?because?
concluding?there?is?a?relationship?between?
variables?when?there?is?not?can?lead?to?more?
extreme?consequences.??A?drug?trial?
illustrates?this?well.??Concluding?falsely?that?
a?drug?can?help?could?lead?to?the?drug?being?
put?on?the?market?without?being?beneficial?
to?the?public.??A?Type?II?error?would?lead?to?
a?promising?drug?being?left?off?the?market,?

Evidence?Based?Library?and?Information?Practice?2007,?2:1?

34

which?while?serious,?isn?t?considered?as?dire.?
To?help?remember?this,?think?of?the?
conservative?nature?of?science.?Inaction?(and?
possibly?more?testing)?is?less?dangerous?
than?action.??Thus,?disproving?the?null?
hypothesis,?which?supposes?no?relationship,?
is?preferred?to?proving?the?alternative?
hypnosis.?
?
There?are?many?safety?features?built?in?to?
research?methodology?which?help?minimize?
the?possibility?of?committing?both?errors,?
including?sampling?techniques?and?
statistical?significance,?both?of?which?you?
will?learn?about?later.?
?
Dependent?and?Independent?Variables?
Understanding?hypotheses?help?you?
determine?which?variables?are?dependent?
and?which?are?independent?(why?this?is?
important?will?be?revealed?a?bit?later).??
Essentially?it?works?like?this:??the?dependent?
variable?(DV)?is?what?you?are?measuring,?
while?the?independent?variable?(IV)?is?the?
cause,?or?predictor,?of?what?is?being?
measured.?
?
In?experimental?research?(research?done?in?
controlled?conditions?like?a?lab),?there?is?
usually?only?one?hypothesis,?and?
determining?the?variables?are?relatively?
simple.?For?example,?in?drug?trials,?the?
dosage?is?the?independent?variable?(what?
the?researcher?is?manipulating)?while?the?
effects?are?dependent?variables?(what?the?
researcher?is?measuring).?
?
In?non-experimental?research?(research?
which?takes?place?in?the??real?world?,?such?as?
survey?research),?determining?your?
dependent?variable(s)?is?less?straightforward.??
The?same?variable?can?be?considered?
independent?for?one?hypothesis?while?
dependent?for?another.?An?example???you?
might?hypothesize?that?hours?spent?in?the?
library?(independent?variable)?are?a?
predictor?of?grade?point?average?(dependent?
variable).?You?might?also?hypothesize?that?

major?(independent?variable)?affects?how?
much?time?students?spend?in?the?library?
(dependent?variable).?Thus,?your?hypothesis?
construction?dictates?your?dependent?and?
independent?variables.?
?
A?final?variable?to?be?aware?of?in?
quantitative?research?is?the?confounding?
variable?(CV).??Also?know?as?lurking?
variables,?a?confounding?variable?is?an?
unacknowledged?factor?in?an?experiment?
which?might?affect?the?relationship?between?
the?other?variables.??The?classic?example?of?a?
confounding?example?affecting?an?
assumption?of?a?relationship?is?that?murder?
rates?and?ice?cream?purchased?are?highly?
correlated?(when?murder?rates?go?up,?so?
does?the?purchase?of?ice?cream?).?What?is?
the?relationship???There?isn?t?one;?both?
variables?are?affected?by?a?third,?
unacknowledged?variable:?hot?weather.??
?
Population,?Samples?&?Sampling?
Although?it?is?possible?to?study?an?entire?
population?(censuses?are?examples?of?this),?
in?research?samples?are?normally?drawn?
from?the?population?to?make?experiments?
feasible.?The?results?of?the?study?are?then?
generalized?to?the?population.??Obviously,?it?
is?important?to?choose?your?sample?wisely!?
?
Population?
This?might?seem?obvious,?but?the?first?step?is?
to?carefully?determine?the?characteristics?of?
the?population?about?which?you?wish?to?
learn.??For?example,?if?your?research?
involves?your?university,?it?is?worthwhile?to?
investigate?the?basic?demographic?features?
of?the?institution;?i.e.,?what?is?the?percentage?
of?undergraduate?students?vs.?graduate?
students???Males?vs.?females???If?you?think?
these?are?groups?you?would?like?to?compare?
in?your?study,?you?must?ensure?they?are?
properly?represented?in?your?sample.?
?
Sampling?Techniques?
Probability?Sampling?

Evidence?Based?Library?and?Information?Practice?2007,?2:1?

35

Probability?sampling?means?that?each?
member?of?the?population?has?an?equal?
chance?of?being?selected?for?the?survey.??
There?are?several?flavors?of?probability?
sampling;?the?common?characteristic?being?
that?in?order?to?perform?probability?
sampling?you?must?be?able?to?identify?all?
members?of?your?population??
?
Random?sampling?is?the?most?basic?form?of?
probability?sampling.?It?involves?identifying?
every?member?of?a?population?(often?by?
assigning?each?a?number),?and?then?
selecting?sample?subjects?by?randomly?
choosing?numbers.?This?is?often?done?by?
computer?programs.?
?
Stratified?random?sampling?ensures?the?
sample?matches?the?population?on?
characteristics?important?to?a?study.?Using?
the?example?of?a?university,?you?might?
separate?your?population?into?graduate?
students?and?undergraduate?students,?and?
then?randomly?sample?each?group?
separately.?This?will?ensure?that?if?your?
university?has?70%?undergraduates?and?30%?
graduates,?your?sample?will?have?a?similar?
ratio.?
?
Cluster?sampling?is?used?when?a?population?
is?spread?over?a?large?geographic?region.??
For?example,?if?you?are?studying?librarians?
who?work?at?public?libraries?in?Canada,?you?
might?randomly?sample?50?libraries,?and?
then?randomly?sample?the?librarians?within?
those?libraries.?
?
Non-probability?Sampling?
Simply?put,?this?is?any?sampling?technique?
that?does?not?involve?random?sampling.??
Often?samples?are?not?random?because?in?
some?research?it?is?easier?to?perform?
convenience?sampling?(surveying?those?who?
volunteer,?for?example).?Also,?sometimes?the?
population?from?which?the?sample?is?to?be?
taken?cannot?be?easily?identified.??A?
common?strategy?employed?by?libraries?is?to?

use?patron?records?to?derive?random?
samples.?This?is?probability?sampling?only?if?
the?population?is?library?users;?if?the?
population?is?an?entire?institution?or?city,?it?
is?no?longer?random.?With?non-probability?
samples,?you?can?only?generalize?to?those?
who?participated,?not?to?a?population.?
?
Sample?Size?
Sample?size?is?also?extremely?important?to?
be?able?to?accurately?generalize?to?a?
population.?Generally,?the?bigger?the?sample,?
the?better.?The?Central?Limit?Theorem?states?
that?the?larger?the?sample,?the?more?likely?
the?distribution?of?the?means?will?be?normal,?
and?therefore?population?characteristics?can?
more?accurately?be?predicted.??Some?other?
things?to?keep?in?mind:?
?

? If?you?want?to?compare?groups?with?
each?other?(for?example,?majors),?
you?will?need?at?least?5?subjects?in?
each?group?to?do?many?statistical?
analyses.?

?
? Poor?response?rate?can?severely?

compromise?a?study,?if?surveys?are?
involved.??Depending?on?the?
distribution?method,?response?rate?
can?be?as?low?as?10%?(ideally?you?
want?a?response?rate?over?70%)?
(Weisberg?119).Ensure?your?sample?
size?is?large?enough?to?still?provide?
accurate?results?with?a?poor?
response?rate.?

?
There?is?no?magic?formula?to?determine?the?
proper?sample?size???it?depends?on?the?
complexity?of?your?research,?how?
homogenous?the?population?is,?and?time?
and?human?resources?you?have?available?to?
compile?and?analyze?data.?
?
Descriptive?Statistics?
Once?you?have?performed?your?research?
and?gathered?data,?you?need?to?perform?

Evidence?Based?Library?and?Information?Practice?2007,?2:1?

36

?
Table?1.?Examples?of?hypotheses.?
?
?
data?analysis.?Choosing?the?appropriate?
statistical?method?for?the?data?is?crucial.??The?
bad?news?is,?this?means?you?have?to?know?a?

whole?lot?about?your?data???is?it?nominal,?
ordinal?or?ratio??Is?it?normally?distributed??
Let?s?start?from?the?very?beginning.?

A?clear?understanding?of?librarians??perceptions?of?EBP?is?necessary?to?inform?the?development?of?
systems?to?support?EBP?in?librarianship.?
?
The?following?research?questions?were?posed:?

1. What?are?the?perceptions?of?librarians?of?EBP??
2. Does?institution?type?the?librarian?works?at?affect?perception??
3. Does?length?of?service?of?the?librarian?affect?perception??

?
What?are?the?hypotheses??
?
There?are?three?being?provided.?Here?is?a?rephrasing?of?number?3:?
?

H0?=??Length?of?service?of?librarians?has?no?affect?on?the?perception?of?EBP??
H1?=??Length?of?service?of?librarians?affects?the?perception?of?EBP??
?

What?are?the?Type?I?&?II?error?possibilities??
?

? ?
????The?real?situation?(in?the?population)?
?
?????????H0?is?true?????????????????????H1?is?true?
?

No?error?
?
?

?
Type?II?error?

?
?
?
Result?of?
Research?????????????????
(from?sample):???????

H0?is?proven?(length?
of?service?doesn?t?
affect?perception)?
?
?
H1?is?proven?(length?
of?service?does?affect?
perception)?

?
Type?I?error?

?
?

?
No?error?

?
What?are?the?dependent?and?independent?variables??
?
The?researchers?are?attempting?to?determine?whether?length?of?service?can?predict?perception?of?EBP,?
or?to?rephrase,?is?perception?of?EBP?dependant?on?length?of?service.?Therefore:?
?

Dependent?variables:?perception?of?EBP?
Independent?variable:?length?of?service?

Evidence?Based?Library?and?Information?Practice?2007,?2:1?

37

Levels?of?Measurement?
Nominal?variables?are?measured?at?the?most?
basic?level.??They?are?discrete?levels?of?
measurement?where?a?number?represents?a?
category?(i.e.,?1?=?male;?2?=?female),?but?these?
numbers?do?not?imply?order?and?
mathematical?calculations?cannot?be?
performed?on?them.??You?could?just?as?easily?
say,?1?=?male?and?36,000?=?female?-?this?
doesn?t?mean?that?females?are?35,?999?times?
bigger?or?better?than?males!?Nominal?
variables?are?of?the?least?use?statistically.?
?
Ordinal?variables?are?also?discrete?categories,?
but?there?is?an?order?to?the?categories;?they?
increase?and?decrease?at?regular?intervals.??A?

good?example?is?a?Likert?scale:??1?=?very?
poor;?2?=?poor;?3?=?average,?etc.?In?this?
example,?you?can?state?1?is??less??or??smaller??
or??worse??than?2.??The?disadvantage?of?
ordinal?variables?is?that?you?cannot?measure?
in?between?the?values.??You?do?not?know?
how?much?worse?1?is?than?2.?
?
Ratio?(sometimes?known?as?scale,?
continuous?or?interval)?variables?are?the?
most?robust,?statistically,?of?variable?types.??
Ratio?variables?have?natural?order,?and?the?
distance?between?the?points?in?the?same.?
Think?of?pounds?on?a?scale.??You?know?that?
?

?
Table?2.?Examples?of?sampling.?
?

The?sampling?frame?was?the?database?of?all?librarians?(defined?as?those?who?hold?an?MLS)?
who?were?members?of?the?Canadian?Library?Association?in?March?2005.??A?total?of?5,683?
librarians?were?on?the?list.?The?list?was?divided?up?by?type?of?library?worked?at?(academic,?
public,?school,?special,?and?other?/?not?stated).?A?proportional?random?sample?of?210?was?then?
selected.?This?ensured?that?even?at?a?return?rate?of?40%?a?final?sample?size?of?150?would?be?
achieved.?
?
Is?this?a?random?sample??
On?first?glance,?yes.??However,?this?is?only?a?true?random?sample?if?all?librarians?in?Canada?
belonged?to?the?Canadian?Library?Association.??The?design?of?this?study?means?that?the?results?
can?only?be?generalized?to?Canadian?Library?Association?members,?not?to?Canadian?librarians.?
?
What?sampling?technique?is?used??
This?survey?used?stratified?random?sampling?to?ensure?that?all?types?of?librarians?would?be?
represented,?as?illustrated?in?the?chart?below.??Pleas