A quantitative research project is characterized by having a population for which the researcher wants to draw conclusions, but it is not possible to collect data on the entire population. For an observational study, it is necessary to select a proper, statistical random sample and to use methods of statistical inference to draw conclusions about the population. For an experimental study, it is necessary to have a random assignment of subjects to experimental and control groups in order to use methods of statistical inference.
Statistical methods are used in all three stages of a quantitative research project. For observational studies, the data are collected using statistical sampling theory. Then, the sample data are analyzed using descriptive statistical analysis. Finally, generalizations are made from the sample data to the entire population using statistical inference. For experimental studies, the subjects are allocated to experimental and control group using randomizing methods. Then, the experimental data are analyzed using descriptive statistical analysis. Finally, just as for observational data, generalizations are made to a larger population.
Iversen, G. (2004). Quantitative research. In M. Lewis-Beck, A. Bryman, & T. Liao (Eds.), Encyclopedia of social science research methods. (pp. 897-898). Thousand Oaks, CA: SAGE Publications, Inc.
This abstract has several indications that this is a quantitative study:
Here's an example of an article that has several quantitative research terms as Minor Subjects in the CINAHL database.
This abstract has several indications that this is a qualitative study:
| Qualitative Research | Quantitative Research | |
| Nature / Purpose | a research method that generates an understanding of the social world; the purpose is to explore and discover ideas | a research method that generates and analyzes numerical data; the purpose it to examine the cause and effect relationship between variables |
| Approach | subjective, process-oriented | objective, outcome-oriented |
| Hypotheses | tentative and evolving; generated | stated up-front; specific and tested |
| Research Setting | a controlled environment is not as important | a controlled environment is very important |
| Sampling | often small, may not be representative (purposive) | often large, desire that they are representative of a population (random) |
| Design & Method | flexible, descriptive | structured, calculates |
| Data | words (verbal), pictures, objects |
numbers (measurable) |
| Methods for Collecting Data |
non-structured techniques: interviews, diaries, observation (people, documents, artifacts), focus groups, field notes, open-ended survey questions, |
structured techniques: observations, questionnaires, surveys |
| Data Analysis | user observations | use numbers & statistics |
| Data Interpretation | conclusions are tentative | conclusions are stated with a degree of certainty |
| Results | develops an initial understanding | recommends a final course of action |
This chart is based on the following sources: Qualitative vs. Quantitative (Diffen), Difference Between Qualitative and Quantitative Research (Key Differences).