14 Quasi-Experimental and Naturalistic Designs Flashcards
why use quasi-experimental/naturalistic?
experimental not feasible or causal relationship not goal
___ design is used to provide reasonable evidence of cause, introduce treatment but no control group
quasi-experimental design
controls in quasi-experimental?
time at which treatment introduced/withdrawn, control group from diff sample
repeated observations before and after treatment
time-series designs
what is time series design steps?
1) select appropriate pop. 2) specify dependent variable 3) introduce treatment to decrease risk factor 4) monitor dependent variable
example of time series design?
introduce package promoting exercise and healthy diet
probs of time series design?
history threat, probs of internal validity
example of multi group time series design?
in community A have control, community B introduce health promotion program
prob of multi group time series?
A and B not equivalent
why naturalistic?
variables can’t be manipulated, ethically inappropriate intervene, multiple causal/risk factors
in naturalistic comparisons, have extraneous variables that can be ____ but not ____
controlled ; manipulated
identifies interrelationships among variables, expresses numerically the strength of association
correlational studies (probabilities)
aim to describe accurately characteristics/variables of populations, provide overview of status/patterns in community
survey
common uses of surveys in health/nutrition:
establish attitudes/opinions/beliefs regarding issue, study characteristics of populations, study demographics of health issues/practices
what are internal validity probs of naturalistic design?
less control over studied phenomena, more difficult exclude alternative explanations/hypotheses
