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Northern Advanced Research Training Initiative Experimental Research Methods. Nikos Bozionelos PhD e-mail: nikos.bozionelos@durham.ac.uk. Experimental Research. Steps in Research. Design Implementation (e.g., data collection) Analysis Results. valid. ?. Validity:
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Northern Advanced Research Training Initiative Experimental Research Methods Nikos Bozionelos PhD e-mail: nikos.bozionelos@durham.ac.uk
Steps in Research Design Implementation (e.g., data collection) Analysis Results valid ?
Validity: the extent to which the explanation that is indicated by the findings is exclusive and sufficient (i.e.,whetheralternative explanations can be ruled out) extraneous factors (i.e., factors outside the scope of the study) may be responsible for the results
Validity: the extent to which the explanation that is indicated by the findings is exclusive and sufficient (i.e.,whetheralternative explanations can be ruled out) extraneous factors (i.e., factors outside the scope of the study) may be responsible for the results confounding
confounding • history • instrumentation (measures) • attrition (“mortality”) • maturation • causality control for confounding to improve validity
confounding imposes threats to the validity of research confounding • history • instrumentation (measures) • attrition (“mortality”) • maturation • causality control for confounding to improve validity
types of validity • internal the extent to which extraneous factors cannot be responsible for the results • external the extent to which the results can be generalised to other settings/environments
internal validity has priority the research method to improve/ensure internal validity is the experiment
experiment:a research study conducted under strictly controlled conditions only two factors/variables are allowed to change: • the Independent Variable (cause) • the Dependent Variable (effect)
experiment:a research study conducted under strictly controlled conditions only two factors/variables are allowed to change: • the Independent Variable (cause) • the Dependent Variable (effect) manipulated by the Researcher changed by the effects of the Independent Variable
aim: to prove with certainty independent variables dependent variables cause allowed to change manipulated by us
types of experiments • laboratory experiment what do we compromise? • field experiment/quasi experiment greater external validity
How do we prove causality? • control group (nochange in the Independent Variable) • experimental group (change in the Independent Variable)
in experiments we must control for: demand characteristics: experimenter and participant effects how? • single-blind & double-blind procedures • automation • objective measures-multiple observers • deception
in experiments we must also control for: the characteristics of participants how? • random selection of participants • random assignment into experimental conditions