Nature and Qualities of Quantitative Research

Quantitative research utilizes numerical values to describe a phenomenon or infer relationships.
It is a primary approach for scientific inquiry due to its ability to test hypotheses.
Variables are traits that numerically describe or give meaning to an object, phenomenon, or group. They are the core elements identified and correlated to answer inquiries.
Independent Variable: The variable that is manipulated, particularly in experiments.
Dependent Variable: The variable that depends on or is affected by the independent variable.

Controllability: Research is conducted in an environment where all variables are identified and can be controlled.
Objectivity: Data results are observable and measured using structured instruments.
Generalizability: Results from large, representative sample sizes can be applied to the broader population.
Replicability: Studies should be repeatable by other research teams to achieve similar outcomes.

According to Queiros, Faria, and Almeida (2017):

Strengths:
- Analysis is assisted by statistical methods.
- Ability to undertake large-scale research.
- Data is presented clearly in graphical or tabular forms.
Weaknesses:
- Large sample sizes require significant time and effort.
- Statistical analysis requires expert performance.
- Reducing observations to numerical values can be too simplistic.

True Experimental Research:
- Primary objective is to identify cause-effect relationships.
- Uses Random Assignment to experimental and control groups to ensure comparability.
- Involves active manipulation of the independent variable in a controlled environment.
Quasi-experimental Research:
- Mirrors experimental research but uses Assigned Samples (pre-existing groups) instead of random ones.
- Used when random assignment is impossible due to innate characteristics (e.g., height).
- Still involves manipulation of an independent variable to infer causality but carries potential selection bias.

Descriptive Research:
- Focuses on describing factors, variables, or phenomena occurring in nature without altering conditions.
- Employs tools like surveys or questionnaires to collect objective measurements.
Comparative Research (Causal-Comparative):
- Compares two or more groups to identify if a causative relationship exists.
- Observes variables as they naturally occur without manipulation.
Correlational Research:
- Identifies and quantifies the degree of association between two variables using the Pearson correlation coefficient (indicated by the Greek letter $\rho$ ).
- Positive Correlation: As one variable increases, the other tends to increase.
- Negative Correlation: As one variable increases, the other tends to decrease.
- No Correlation: A coefficient close to zero, indicating little to no relationship.

Quantitative studies can be identified in abstracts by objectives seeking to generalize phenomena or relationships.
Presence of statistical values such as the $\text{p-value}$ , $\rho$ , or descriptive statistics like $\text{mean}$ , $\text{median}$ , and $\text{mode}$ indicates a quantitative approach.
Discrete variables that can be quantified are a hallmark of this research type.