Quantitative Research Approach: Methods, Designs, and Variable Control
Quantitative Research Approach
Introduction
The quantitative approach is a systematic and objective method for collecting, processing, and analyzing numerical data to establish relationships between variables and test hypotheses. It involves the use of mathematical and statistical techniques to quantify and analyze data.
Features of Quantitative Research
- Variability: Observations on the same issue with different values.
- Validity: The extent to which scientific explanations of events coincide with reality.
- Internal Validity: External variables are taken into account or controlled.
- External Validity: Results and generalizations can be applied to other people and environments.
- Reliability: The ability of a measurement to capture the relationship between variables.
- Simplicity: The research design should not be overly complex.
- Level of Significance: The probability of obtaining the observed results by chance.
Methods of Quantitative Research
- Experimental: High degree of control. The researcher manipulates the phenomenon and determines the values of the independent variables. Full control of extraneous variables.
- Quasi-Experimental: Average degree of control. The researcher manipulates the phenomenon and determines the values of the independent variables. Not entirely control extraneous variables.
- Non-Experimental: Low degree of control. No change to the phenomenon and the relationship between variables has already occurred. The researcher can only register their measures.
Defining Variables
- Operationalized: Variables are defined in terms of observable and measurable characteristics.
- Nominal Scale: Classification identifying individuals.
- Ordinal Scale: Operationalizes variables indicating the order.
- Interval Scale: Gives numerical values to individuals to set their differences.
- Ratio Scale: Adds the existence of absolute zero.
- Constitutive: Describes the essence of an object or phenomenon defined as a dictionary. Its variables are not directly observable and it does not suffice to test the hypothesis.
Control of Variables
- Independent Variable: The variable that is manipulated or selected to determine its effect on the dependent variable.
- Handling: Values of the independent variable are varied to observe changes in the dependent variable.
- Selection: When there is no manipulation of the independent variable.
- Dependent Variable: The variable that is measured to determine the effect of the independent variable.
- Number of Steps, Time of Measurement: Can be before (pretest), after (post-test), or differential test (delayed effect).
- Extraneous Variable: Variables that are not part of the research design but may influence the results.
Quantitative Research Designs
Pre-Experimental Designs
- Post-test with One Group: Provide treatment and then observe.
- Post-test-Post-test with One Group: Pre-test, treatment, and after post-test (the result obtained is the change).
- Post-test with Two Nonequivalent Groups: Including a control group that received no treatment.
Experimental Designs
- Named in Physical and Biological Sciences
Quasi-Experimental Designs
- Pre-test-Post-test with a Non-Equivalent Control Group: Groups of subjects already established.
- Interleaved Time Series by a Group: A group was many observations before and after treatment.
- Interrupted Time Series with Control Groups: To improve the previous design.
- Of a Single Subject: Similar to above but involved only one subject.
Non-Experimental Designs
- Social Research and Educational Means After the Fact
- Data collected after the occurrence of the alleged causes.
- Do not have flexible control over independent variables.
- Flexible method for establishing the hypothesis.
- Conceived as a survey.
- Types:
- Descriptive Studies: A first approximation to reality.
- Poll Studies: Use questionnaires and interviews.
- Prerequisites for the Design of Any Survey:
- Clear purpose of the investigation.
- Determine the population on which to focus.
- Be aware of available resources.
- Phases:
- Defining the objectives of the questionnaire survey planning.
- Development and selection of questions.
- Analysis of the quality of the questions.
- Analysis of the reliability and validity of the questionnaire (pilot testing, validating judges).