Overview of Quantitative
Research: Definition
❑is a formal, objective, systematic process in which numerical data are
utilized to obtain information about the world
❑the systematic empirical investigation of observable phenomena via
statistical, mathematicaland computational techniques
Overview of Quantitative
Research: Definition
❑used to examine the relationship between variables with the primary goal
being to analyze and represent that relationship mathematically through
statistical analysis
❑the type of research approach most commonly used in scientific research
problems (natural sciences, social sciences, etc.)
Overview of Quantitative
Research
Quantitativeresearchisgenerallymadeusingscientific
methods,whichcaninclude:
❑thegenerationofmodels,theoriesandhypotheses
❑thedevelopmentofinstrumentsandmethodsfor
measurement
❑experimentalcontrolandmanipulationofvariables
❑collectionofempiricaldata
❑modelling and analysis of data
Characteristics of Quantitative
Research
1. The data collected is numeric,
allowing for collection of data
from a large sample size.
Characteristics of Quantitative
Research
2. Statistical analysis allows
for greater objectivity when
reviewing results and
therefore, results are
independent of the
researcher
Characteristics of Quantitative
Research
3. Numerical results can be
displayed in graphs, charts, tables
and other formats that allow for
better interpretation.
Characteristics of Quantitative
Research
4. Data analysis is less time-consuming and can often be done using
statistical software.
Characteristics of Quantitative
Research
5. Results can be generalized if the data are based on random
samples and the sample size was sufficient.
Characteristics of Quantitative
Research
6. Data collection methods can be relatively quick, depending on the type
of data being collected.
7. Numerical quantitative data may be viewed as more credible and
reliable, especially to policy makers, decision makers, and administrators.
Quantitative Research
Examplesofresearchquestionswherequantitativemethodsmaybe
appropriatelyapplied:
▪How often do college students between the ages of 20-24 access Facebook?
▪What is the difference in the number of calories consumed between male
and female high school students?
▪What percentage of married couples seek couples counseling?
▪What are the top 5 factors that influence a student’s choice of college or
university?
▪How many organized sports activities has the average 10 year old child
competed in?
When to Use Quantitative
Methods
Researchers should begin by asking
themselves the following questions:
➢What type of question am I asking?
➢What type of data will I need to
collect to answer the question?
➢What type of results will I report?
When to Use Quantitative
Methods
Key Issues in Quantitative
Research
Validity ReliabilityReplicability
GeneralizabilityFalsifiability
1. Validity
◦refers to thestrength of the
conclusionsthat are drawn from
the results
◦How accurateare the results?
◦Do the results actually measure
what was intended to be
measured?
Key Issues in Quantitative
Research
▪Conclusionvalidity-degreetowhichtheconclusioniscredibleorbelievable
▪Internal validity -extent to which the independent variable can accurately be stated to
produce the observed effect
▪Construct validity -degree to which a test of measurement accurately assess the theoretical
construct it intends to measure or it is an attempt to generalize the treatment and outcomes
to a broader concept.
▪External validity -ability to generalize the results to another setting.It examines whether the
findings of a study can be generalized to other contexts
▪Criterion-related validity (also called instrumental validity) is a measure of the quality of your
measurement methods. The accuracy of a measure is demonstrated by comparing it with a
measure that is already known to be valid
Key Issues in Quantitative
Research
Key Issues in Quantitative
Research
1. Validity
2. Reliability
❑consistencyofthemeasurements-towhatlevelwillthe
instrumentproducethesameresultsunderthesameconditions
everytimeitisused?
❑whether research methods can reproduce the same results
multiple times.
❑If your research methods can produce consistent results, then
the methods are likely reliable and not influenced by external
factors
RELIABILITY
❑Internal reliabilityrefers to how consistently different items within
a single test measure the same concept or construct. It ensures
that a test is stable across its components.
❑External reliabilitymeasures how consistently a test produces
similar results over repeated administrations or under different
conditions. It ensures that a test is stable over time and situations.
Key Issues in Quantitative
Research
Falsifiability/Testability
❑means that any for any hypothesis to have
credence, it must be possible to test whether that
hypothesis may be incorrect
❑A researcher should test his/her own hypothesis
to prove or disprove it before releasing results to
prevent another researcher from proving it wrong.
❑If a theory or hypothesis cannot be tested in
such a way that may disprove it, it will likely not be
considered scientific or valuable to those in the
field.
Key Issues in Quantitative
Research
Generalizability
❑refers to whether or not the research findings and
conclusions that result from the study are generalizable to
the larger population or other similar situations.
❑The ability to generalize results allows researchers to
interpret and apply findings in a broader context, making
the finding relevant and meaningful.
Key Issues in Quantitative
Research
Replicability
the reproducibility of the study
◦Will the methodology produce the same results when
used by different researchers studying similar subjects?
it ensures the validity and reliability of the results and
allows the results to be generalized
Quantitative Scales of
Measurement
Quantitative research requires that measurements be
both accurateand reliable.
Researchers commonly assign numbers or values to
the attributes of people, objects, events, perceptions,
or concepts.
This process is referred to as measurement.
❑referstothevariousmeasuresusedinquantifyingthevariables
researchersuseInperformingdataanalysis.
❑Theyareanimportantaspectofresearchandstatisticsbecause
thelevelofdatameasurementiswhatdeterminesthedata
analysistechniquetobeused
❑prerequisitetoworkingwithdataandperformingstatistical
analysis
SCALES OF MEASUREMENT
MAGNITUDE (ORDER)
❑the size of a measurement scale, where numbers (the identity) have an
inherent order from least to highest.
❑They are usually represented on the scale in ascending or descending order.
The position in a race, for example, is arranged from the 1st, 2nd, 3rd to the
least.
❑This example is measured on an ordinal scale because it has both identity
and magnitude
Characteristics of a Measurement
Scale
EQUAL INTERVALS (DISTANCE)
❑thescalethathasastandardizedorder.I.e.,thedifference
betweeneachlevelonthescaleisthesame
❑Avariablethathasanidentity,magnitude,andequalintervalis
measuredonanintervalscale.
Characteristics of a Measurement
Scale
ABSOLUTE ZERO (ORIGIN)
❑definedasthefeaturethatisuniquetoaratioscale.
❑Itmeansthatthereisanexistenceofzeroonthescale,andis
definedbytheabsenceofthevariablebeingmeasured
Characteristics of a Measurement
Scale
Primary Scales of Measurement
1. Nominal Scale
❑used for identification purposes
❑categoricalscale,itassignsnumberstoattributesforeasyidentity.These
numbersarehowevernotqualitativeinnatureandonlyactaslabels.
❑Theonlystatisticalanalysisthatcanbeperformedonanominalscaleis
thepercentageorfrequencycount.Itcanbeanalyzedgraphicallyusinga
barchartandpiechart.
❑1Male,2Female/1Single2Married3Widow
Quantitative Data
❑data that can be counted or expressed numerically
❑It is commonly used to ask “how much” or “how many” and can
be used to study events or levels of occurrence.
❑Because it is numerical in nature, quantitative data is both
definitive and objective
❑statistical analysis and mathematical computations and therefore,
is typically illustrated in charts or graphs.
Discretedata-wholenumbersthatcan’tbedividedorbroken
intoindividualparts,fractionsordecimals;describedashaving
afinitenumberofpossiblevalues
Continuousdataarevaluesthatcanbebrokendowninto
differentparts,units,fractionsanddecimals;usuallyaphysical
measurement.
2 Main Types
Quantitative Data
DATA COLLECTION
❑systematicprocessofgatheringobservationsor
measurements
▪Theaimof the research
▪Thetype of datathat will be collected
▪Themethodsand proceduresto be used, stored, and
processed the data
Methods of Data Collection
❑Experiments and clinical trials
❑Surveys, interviews and questionnaires
❑Observing or recording well-defined events
❑Obtaining information from a management
information system.
Sampling
▪Process of selecting a sampleor portion of a larger group of
potential participants in order to generalize statements about a
broader group or population
▪In general, sample size (n) is chosen in order to reproduce some
characteristics of the whole population (N).
▪Sound sampling method will result to a bias free and reliable
results (representative of the population of interest)
Sampling Process
Theoretical or
Target Population
Source: Salkind(2010)
Accessible
Population
or
Sampling Frame
Select
Sample
Actual
Sample
SAMPLE
▪Subset of a population
▪specific group of individuals that you will collect data
from
▪sample size depends on the size andvariabilityof the
populationand research design
POPULATION
▪Group from which a sample is drawn
▪Exact population will depend on the scope of the study
▪The entire group that you want to draw conclusions
about
SAMPLING FRAME
▪the actual list of individuals that the sample will be
drawn from
Collecting data from a population
❑Populationsareusedwhenyourresearchquestionrequires,orwhenyou
haveaccessto,datafromeverymemberofthepopulation.
❑Usually,itisonlystraightforwardtocollectdatafromawholepopulation
whenitissmall,accessibleandcooperative
Collecting data from a sample
❑Whenyourpopulationislargeinsize,geographicallydispersed,ordifficult
tocontact,it’snecessarytouseasample.
❑Withstatisticalanalysis,youcanusesampledatatomakeestimatesor
testhypothesesaboutpopulationdata
METHODS of SAMPLING
1.Probability Sampling
2.Non-probability Sampling
PROBABILITY SAMPLING
Use randomizationto generate
representative samples from the
target population
Randomization increases the likely
hood of getting representative
samples
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Sampling Procedures
Probability Sampling
1.Simple Random Sampling
▪Simplest form of probability sampling
▪Sample size (n) is taken from every possible subset of n in the
population
▪every member of the population has an equal chance of being
selected
▪Provides foundation for other complicated sampling schemes
▪Sampling frame should include the whole population
Simple Random Sampling
Probability Sampling
2.Stratified Random Sampling
◦Target population is divided into strata
◦Split population into strata and then randomly select from
each of these subgroups
◦Strata could be a sub-group of interest, attributesor
characteristics(e.g. region, age group, grade level)
◦Stratificationoften increase precision
Probability Sampling
3.Cluster Sampling
◦divide the sample into clusters that approximately
reflect the whole population, and then choose
sample from a random selection of these clusters
◦A cluster is similar to a stratum, clusters, such as
districts, schools, municipality
◦Clustering decreases precision
divide into clusters based on age, gender, location, etc., and then selects
customer a random sample from each cluster for further analysis
Probability Sampling
4.Systematic Sampling
◦Proxy for simple random sampling when list of
population is non existent.
◦Choosing sample based on a regular interval
◦From the starting starting point, samples are taken
every kth unit after resulting to equally space
sampling unit within the list
Systematic Sampling
select members of the population
at a regular interval–for example,
by selecting every 5th person on a
list of the population
Nonprobability Sampling
1. Convenience
❑includes the individuals who happen to be most
accessible to the researcher
❑Reasons due to geographical proximity, availability at a
given time, or willingness to participate in the research
❑Haphazard or accidental sampling
Choose who or what is available during the survey or study
Nonprobability Sampling
2. Quota
◦Similar to stratified random sampling but with no randomization
◦Relies on the non-random selection of a predetermined (quota)
number of samples
◦Divide the population into mutually exclusive subgroups (called
strata) and then recruit sample units until you reach your quota
◦Judgmental sampling
enlists study participants until a relevant research category (or quota) has
recruited enough respondents to reach holistic conclusions
Nonprobability Sampling
3.Snowball
▪Used to collect data from people who are for reason hard
to identify
▪existing subjects provide referrals to
recruit samplesrequired for a research study
▪purely based on referrals and that is how a researcher is
able to generate a sample.
▪Therefore this method is also called the chain-referralor
network sampling method
4.Purposive (Purposeful Sampling)
❑Selecting samples from the overall sample size based on the
judgment of the survey taker or researcher
❑Samples are identified base certain criteria/requirements the
study demands
❑Set out to identify members of the population who are likely to
possess certain characteristics or experiences
❑Select the individuals or cases that fit your study, focusing on a
relatively small sample
Nonprobability Sampling