Quiz 9 Flashcards
Non-experimental Research Designs
Research designs in which an experimenter simply either describes a group or examines relationships between existing groups. Describes the problem through observing changes to variables that occur without incorporating any manipulation on the part of the researcher. The focus is to describe what develops naturally.
Does not manipulate variables
-Does not seek to identify causal relationships
-Seeks to discover relationships
Typically involves one group
Sampling Methods
-Numerous – both probability and non-probability
Characteristics of non-experimental designs
- Typically involves one sample group
- Uses probability and non-probability sampling methods (DOES NOT use purposive and theoretical sampling methods)
- Do not manipulate variables.
Why choose a non-experimental research design
Non-experimental research design is often used:
-When it may be unethical or not feasible to conduct an experimental design.
- When the researcher is looking to study a rare outcome.
- When the research involves only one sample.
- When the researcher is looking to explore a topic before deciding whether or not to examine it further with an experimental design.
- When the research is looking to establish past relationships or associations between variables.
Developmental Designs
Study characteristics or variables as they develop or change over time
-Cross-sectional and Longitudinal
Developmental Designs : Cross sectional
Takes a snapshot of stages of development from different groups at the same time.
Researcher collects data one time from different groups to simulate development over time.
Allows for quick, inexpensive data collection.
Low internal validity due to possibility of confounding variables
-1 data collection point for respondent
-development is shown through the differences that exist between groups
-does NOT utilize a control or comparison group
ex: . For example if the researcher wants to look at maturation across a span of 4 years in high school the researcher will collect data from groups of freshman, sophomores, juniors, and seniors and analyze it together to see change over time
- confounding variables could be an issue
Developmental Designs : Cross sectional Example
Objective:To assess the impact of breast feeding on the risk of obesity and risk of being overweight in children at the time of entry to school.
Methods:Routine data were collected on the height and weight of 134,577 children participating in the obligatory health examination at the time of school entry. Mothers were surveyed on breast feeding practices.
Main outcome measures:Being overweight was defined as having a body mass index above the 90th percentile and obesity was defined as body mass index above the 97th percentile of all enrolled children. Exclusive breast feeding was defined as the child being fed no food other than breast milk.
Results:The prevalence of obesity in children who had never been breast fed was 4.5% as compared with 2.8% in breastfed children.
Conclusions:In industrialized countries promoting prolonged breast feeding may help decrease the prevalence of obesity in childhood.
Developmental Designs: Longtidunal Studies
Follows a group (cohort) over a period of time to study development.
Allows for the researcher to set up multiple data collection points over the life of the study and look at multiple variables.
Often expensive and requires a team of researchers.
High rate of attrition (loss to follow up.
ex:In a longitudinal study the researcher would follow a group of incoming freshman for 4 years, and collect data once a year to look at the maturation of one group.
Observational Research Design
Records naturally occurring behavior to better understand what behavior is occurring
Quan Observational Research
Quantitative observational design differs from using observation to collect data in a qualitative study
-Operational Definition:
*provides strict guidelines as to what should be observed, counted, and evaluated during the study
Data Collection
-Prespecified focus to observations, underlying theoretical framework
-Operational define what is being observed in order to count or evaluate observation
-Collecting of data is done in small segments of time
-Codes are predetermined backed on theory
-Rating scale is used to evaluate the observation
-More than one independent raters
-Involves in-depth training of team and raters to ensure consistency
Observational Design: Code in Qualitative research
Codes are determined after the data collection occurs. Here the word code is defined as the interpretation of a meaning unit and is associated with the data analysis process
Observational Design: Code in QUAN research
Codes are how the researcher quanitfies the observation (collects data). The individuals who collect data, often called raters, are made aware of what type of data they will be collecting before the study even begins. The raters collect data using rating scale that is made up of these predetermined codes
Cohort Research Design
Used to determine if an exposure is linked to the development of a disease or outcome when the relationship between the two has not yet been determined
Cohort Research Design: Prospective
Looks forward to see if an outcome develops from already known exposure Can follow a Single cohort – exposure Two cohorts – exposure/no exposure Can take long to complete
Study begins with the identification of a population and exposure status (exposed/not exposed groups)
Population is followed over a period of time for the development of disease
Cohort Research Design: Retrospective
Looks back into existing data via medical records or subject recall to identify if exposures could be linked to an outcome or disease
Outcome could or could not be present at the start of the study
Quick and inexpensive
Previously collected data is reviewed to identify the population and the exposure status (exposed/not exposed groups)
Determines at present the (development) status of disease
What is the difference between prospective cohort and developmental (longitudinal) studies?
Developmental (longtidunal):
Follows a group over time to study developmental issues (e.g. quality of life).
Prospective (Cohort)
Follows a cohort to determine whether exposure to a risk factor leads to the development of an outcome.
*While cohort studies are longitudinal, not all longitudinal studies would be classified as cohort.