Download - Sampling process and measurement scale
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The DataCollection Process:
ResearchBy: Bryan Mae Degorio
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Objectives:
Defne population and population sample.Discuss probability and nonprobability
methods o sampling.
Discuss the dierent procedures used ineach sampling method including theiradvantages and disadvantages.
Criticize the sampling procedures used in
dierent articles or research report.
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Content:
&opulation sampling
'ypes o sampling
%ampling procedures(ethods o data
collections)
* intervie#+
,uestionnaire+ observationalprocedure+ li-ert scale+mechanical instrument andpsychological or sociologicalinstrument
(easurement o
variables in researchData processing
Data analysis andinterpretation.
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Population and Sampling Process
Population reers to the complete
set o persons or
objects that possessthe same character ointerest to theresearcher.
! "roup o Population
a. 'arget population
b. %tudy population
Samples ! subseto population
selected to represent thepopulation
Sample rame# a list o #hich thesampling unit #ithin apopulation are individuallynamed or numbered
$lement
* reers to the singlemember o a population
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Men bet%een !!' in Canada
Men bet%een !!' in Ontario
(ou prepare asample rame orthose men inOntario# name or
numberThe ) o sampleyou %ill ta*eamong those menin Ontario
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Sampling is the method o selecting sample rom the population
'ypes o sampling
a. &robability sampling
b. $on* probability sampling
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Probabilitysampling+
!-a) Randomsampling
t involves the use o
random samplingselection process toobtain sample or anelement o a
populationts main goal is to
obtainrepresentative
elements o theo ulation.
Types o ProbabilitySampling:
1. %imple randomsampling
2. %tratifed randomsampling
3. Cluster randomsampling
. %ystematic randomsampling
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http)//stattre-.com/statistics/random*number*gene
rator.asp
http://stattrek.com/statistics/random-number-generator.aspxhttp://stattrek.com/statistics/random-number-generator.aspxhttp://stattrek.com/statistics/random-number-generator.aspxhttp://stattrek.com/statistics/random-number-generator.aspxhttp://stattrek.com/statistics/random-number-generator.aspxhttp://stattrek.com/statistics/random-number-generator.aspxhttp://stattrek.com/statistics/random-number-generator.aspx -
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,on#Probability Sampling4'he sample element
are chosen rom thepopulation be anonrandommethod
'here is no %ay thatthe probability obeing included in theparticular samplecan bedetermined-
Types o non#probability sampling:
1. Conveniencesampling
2. 5uota sampling
3. &urposive sampling11/23/1 !pollo "ram#ell $ursing %chool 6
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Deciding the S.MP/$ S01$+
$ote) there is ,O$2.CT value
%uggestions)a. 7btain as manysub8ects as possible
b. 'hings to consider)
data collection techni,ue &rocedure or recruitment
'he cost
9ternal validity
:hen to ta-e largesamples)
1. (any uncontrolled variablesare present
2. %mall dierences are epectedin members o population
3. &opulation must be divided into
subgroups. Drop*out rate is epected to be
high
. %tatistical test are used thatre,uires minimum sample size
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a- Po%er analysis# isa procedure use to
determine thesample size
b- Sampling error#the dierencebet#een the data
obtained rom therandom sample andthe data that #ouldbeen obtained i anentire population#ere measured
c- Sampling bias#occurs #hen thesamples are notcorrectly selected.
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Sample Si3e
4,5
Margin o $rror
4raction5
Margin o $rror
4percentage5
6& ;.31 31.
!& ;.22 22.
7& ;.11 1.16&& ;.1;; 1;.;
!&& ;.;01 0.1
7&& ;.; .
6&&& ;.;32 3.2
!&&& ;.;22 2.2
7&&& ;.;1 1.
6&&&& ;.;1; 1.;
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Measurements+-
s the processassigning numbersto variables.
t implies8uanti9cation ovariables orinormationby
assigning number toa data.
/evels oMeasurements:
1. $ominal scale
2. 7rdinal scale3. nterval scale
. nternal scale
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,ominal Scale $umbers are assigned to
variables that are mutuallyeclusive and dierent romone another.
$: 6; male and !;emale
0nterval Scale
'here is an actual e,ual intervalsize bet#een measurements
!bsence o zeros points
9: Temperature< /i*ert scale
Ordinal Scale !n order/ran-ing is imposed on
categories and the number mustpreserve orders.
'he distance bet#een ran-s are
not e,ual or sometimes notmeasured.
$: 6; tallest< !; nettallest< =rdthird tallest
Ratio Scale
'he highest orm o measurement. 'here is continuum o values #ith
an absolute zero points
9) age< gender< test scores
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$rrors in Measurement+
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Reliability# Reers to the consistency
%ith %hich the instrumentor test measures %hateverit is suppose to measure
(easures o reliability)
a. 'est*retest reliability
b. nternal consistencyvalidity
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Data Collection Methods+
Things to consider in data collection:
a. :ho #ill collect the data
b. :hen the data #ill be collected=
c. :here the data #ill be collected=
d. :hat data #ill be collected=e. >o# the date #ill be collected=
(ethods4.
1. 7bservational methods2. ntervie#s
3. 5uestionnaire
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