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Research Design. Research design refers to the plan or organization of a scientific investigation (development of a plan or strategy that will guide the collection and analysis of data and enhance the researcher’s confidence in the outcomes of a research project.
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Research Design Research design refers to the plan or organization of a scientific investigation (development of a plan or strategy that will guide the collection and analysis of data and enhance the researcher’s confidence in the outcomes of a research project.
Purposes and dimensions of research design • Will there be an intervention ? • What type of comparisons will be made? • What procedures will be used to control extraneous variables? • When and how many will data be collected from research subjects? • In what setting will study take place?
Types of research Design • Experimental research Design: Characteristics of true experiments: • Manipulation: The experimenter does something to at least some of the subject in the study. • Control: including the use of a control group. • experimental group: the group that receives the treatment of interest .
Control group[: refers to a group of subjects whose performance on a dependent variables is used as a basis for evaluating the performance of the experimental group. • Randomization: The experimenter assigns subjects to a control or experimental group on a random basis. • Random: Every subject has an equal chance of being included in any group
Then there is no systematic bias in the groups • Randomization remains the most trustworthy and acceptable method of equalizing groups. Methods for randomization. • Flip a coin • Slips of papers (pulling name form a hat). • Table of random number.
In order to control subject characteristics that are likely to affect the experimental outcome • Advantages of true experiments. • The most powerful method available to scientists for testing hypotheses of cause- and- effect relationships between variables. • Offers greater corroboration than any other research approach. That the independent variable has an effect on the dependent variable.
The great strength of experiments, then, lies in the confidence with which causal relationships can be inferred. There are three criteria for causality:- • A cause must precede an effect in time. • There must an empirical relationship between the presumed cause and presumed effect. • The relationship cannot be explained as being due to the influence of a third variable.
Disadvantages of true experiments: • There are a number of interesting variables that are not amenable to experimental manipulation. • Ethical considerations prohibit their manipulation. • Hawthorne effect: Occurs when study participants aware of being included in a study this cause people to change their behavior there are by obscuring the effect of the variable of inters.
To overcome this problem double- blind experiments may be used by the investigator. In which neither the subjects nor those who administer the treatment know who is in the experimental or control group . • Quasi – experimental research and pre- experimental research.
Advantages and disadvantage, of quasi experiments: • The great strength of quasi experimental lies in their practicality, feasibility when it is impractical to conduct- true- experiments. • Much of the researchers that is of interest to nurses occurs in natural settings. 2.Quasi- experimental designs introduce some research experimental designs introduce some research controls when full experiment is lacking.
The major disadvantage of quasi experiments is that: the kinds of cause and effect inferences cannot be made as easily as with true experiments. -In other words it will weakens the researcher’s ability to make causal inferences.
Nonexperimental research Types of Nonexperimental research. • Ex-post facto research (correlationaI research) • Descriptive research 1.Ex – post-facto research • Ex –post facto is a Latin term means” form after the fact”
Ex – post- facto research” is the systematic empirical inquiry in which the scientist does not have direct control of independent variables because their manifestations have already occurred or because they are inherently not manipulable. Ex –post- facto research does not prove cause and effect relationships.
Ex- post- facto is sometimes described as either: A- Retrospective studies: -start with effect and look back in time to search for cause. b. Prospective studies: - Start with causes and then goes Forward in time to see effect.
- Descriptive research Are not concerned with relationships among variables. Their purpose is to observe, describe and document aspects of a situation. • Some additional types of non-experimental research • Survey research. • Evaluation research. • Need assessment research. • Historical research.
Advantages of non-experimental research • Play a crucial role in nursing because many problems are not amenable to experimentation. • Correlational research is an efficient and effective means of collecting a large amount of data about a problem. • Ex- post- facto researches is strong in realism and try to solve many practical problem . And seldom criticized for its artificiality.
Disadvantages of non experimental research • The inability to randomly assign individual to experimental treatments (pre existing groups that have not formed by random process). • The in ability to actively manipulate the independent variables of interest. • The possibility of faulty interpretation of study results.
Types of research design according to the time dimension: • Cross- sectional designs • Longitudinal designs Collect data at more than one point in time. Types of longitudinal studies A- Trend studies: in which samples from a general population are studied over time. Different simples are selected at repeated intervals, but the samples are always drown from the same population B-Panel studies: The same subjects are used to supply the data at two or more pints in Time. C- Follow up studies similar to panel studies.
