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Quantitative Research Methodolgy
Transcript of Quantitative Research Methodolgy
Operationalizing a variable means
finding a measurable, quantifiable, and valid index for your variable, and (sometimes) finding a way to manipulate that variable,
creating two or more levels. Independent (cause) Variables Dependent (effect) Variables Independent Variables
Methods Presented by:
Connie Omari &
Karen McGibbon Research begins with ideas Factors that are:
objective, effort independent or involuntary, and concrete are more easily measured (with appropriate equipment).
Factors that are:
subjective, effort dependent, or abstract are hard to measure.
(with appropriate equipment):
Weight, arterial oxygen saturation, venous lactate concentration, leg length, etc.
Not easily measured:
Sportsmanship, aggressiveness, pain, basketball ability, love, hunger, frustration, readability, situation awareness, workload, etc. -multiple operational definitions – look to see if the results from different measures of the same concept give the same results
-correlation with another measure that has previously been shown to be valid
-advantageous if at least one operational definition is behaviorally based
-When setting up different Levels of an operational variable, preliminary tests can be done to establish the validity of the level No single operational definition of an abstract concept can encompass that concept completely
First step is to see what has been done in the past (literature search), and if already-devised techniques for defining a variable are applicable to your study
Reliability of the operational definition must be established – the operational scoring system should give the same result for the same sample
-Intra- and inter-observer reliability
Validity of the operational definition must be established •That conditions vary on the intended dimension
•That conditions do not vary on other dimensions
•That treatments are implemented in the intended fashion
•Make inquiries of the participants or independent raters to judge the experimental materials
•Statistically Significant Results
•Statistically Non-significant Results •Variables that are not amenable to manipulation due to either ethical constraints or to logical impossibilities
•More difficult to make causal inferences because they cannot be manipulated Writing Assumptions So how do I start? An Assumption
is something that is
taken to be true
even though the
of its truth is either
absent or very limited The possibility of
significance yet another way to say the same thing Participants The Analysis The
Phenomenon The Instrument The theory (cc) photo by theaucitron on Flickr (cc) photo by theaucitron on Flickr Types of Assumptions and finally... Note Card 1 Source 3 Chicken pox spreads very easily and is identified by its "rash consisting of blisterlike lesions that appear two to three weeks after infection" ("Chicken Pox"). What should it contain? Either the term subjects or participants Describe your informed consent & confidentiality procedures Readers should be able to visualize participants But, Describe only the most relevant issues being studied The population should be named and method of sampling described Limitations are
weaknesses or flaws in the
methodology Writing Delimitations Once a source card is made, students can feel free to start making note cards.
Variables Assumptions are made about The Methodolgy and results remember to name the major ones!
discuss them in some detail
state the reason you believe it is true
if it is questionable, then it may be a... Limitations
the researcher has
no control Acknowledging limitations
reduces the likelihood of
the reader raising those issues
to criticise your argument
or dispute your findings. When writing
Assumptions: eg. hypothesis:
"he who dies with the most toys wins" are boundaries deliberately set
within the study
are under the control of the
eg. geographical location,
variables, instruments Why Operationalize?
Not all variables are easily measured Issues to consider Validity can be established by.... Operationalizing
Variables •Determine the conditions or levels of the independent variable
•Adequately reflect the constructs designated as the cause in the research question
•Limit differences between conditions - ensuring that independent variables differ along the dimensions of interest in which they should differ,
•Establish the salience of differences in conditions Necessary Steps Necessary Manipulation Checks Status Variable are... •Psychometric issues of reliability and validity
•Reactivity - to ensure that the dependent variable does not react with the treatment
•Procedural issues - total administration time of dependent variables, order of presentation, and the reading level of the instruments Process concerned with... Random response error
Scoring and recording errors
Compounding errors many sources of error… Reliability issues Construct validity - degree to which the scores reflect the desired construct rather than some other construct
Convergent validity - the degree to which two measures of constructs that theoretically should be related, are in fact related
Discriminant validity tests - whether concepts or measurements that are supposed to be unrelated are, in fact, unrelated Validity Issues Variables that affect the characteristics of the participants
that are intended to be measured, eg. a test anxious person taking a test may present with increased anxiety because responding to the questions
is like taking a test Reactivity Issues •Time involved with the assessment
•Readability of assessments must be double checked and ensured for accuracy
•Order of the administration of instruments can have an effect on responses; one instrument may influences responses on another instrument
•Alternative forms of repeated measures which allows for a pretest and post-test without having to use the identical instrument Procedural Considerations! Quantitative Research Methodology State numbers, reasons and information on 'dropouts' Describe individual participants if sample is small describe published & unpublished instruments unpublished....in detail report on validity & reliability for both! Describe procedures, equipment, & other mechanical matters well enough so that the study can be replicated.