Types of Research Designs

Research design = blueprint or plan of action to answer research questions.
Broadly classified into:

Experimental Research Design; Involves true manipulation of independent variable (IV), randomization of subjects, and control of extraneous variables.

• Gold standard for establishing cause-effect relationship.
• Follows MAXMINCON principle (maximize variance, minimize error, control extraneous).

Key Characteristics: Random assignment of subjects into groups. Control group present. Manipulation of IV. High internal validity.

Types of Experimental Designs:

• Pre-test Post-test Control Group Design; Two groups: Experimental (treatment) & Control (no treatment). Both tested before & after. Example: Measuring knowledge gain before and after training program.
• Post-test Only Control Group Design; No pre-test, only post-test comparison. Suitable when pre-test may sensitize participants.
• Factorial Design; Examines effect of more than one IV at the same time. Example: Effect of teaching method × gender on adoption.
• Randomized Block Design (RBD); Subjects blocked into homogeneous groups; treatments randomized within blocks.
• Latin Square Design; Used to control two sources of extraneous variation simultaneously.

2. Quasi-Experimental Research Design; Used when true experimental conditions (randomization/control) are not fully possible.

• Common in social sciences, extension education, field research.
• Establishes cause-effect with less control than true experiments.

Key Characteristics:

• No full randomization (groups may be pre-existing).
• May/may not have a control group.
• More practical, but lower internal validity.

Types of Quasi-Experimental Designs:

• Non-equivalent Control Group Design; Experimental & control groups exist but not randomly assigned. Example: Testing new extension approach in one village vs. traditional approach in another.
• Time-Series Design; Multiple observations before and after treatment. Example: Adoption rate of a new crop technology observed for several seasons.
• Counterbalanced Design; All groups receive all treatments, but in different orders. Useful when randomization is difficult.
• Regression-Discontinuity Design; Groups assigned based on a cutoff score (e.g., income level, education).

3. Cross-Sectional Research Design; A research design in which data are collected at one point of time from different individuals, groups, or situations.

• Like taking a snapshot of the population.
• Useful for studying prevalence, relationships, patterns.

Characteristics

• One-time data collection.
• Large samples often used.
• Quick, economical, less resource-intensive.
• Cannot establish cause-effect (only associations).

4. Longitudinal Research Design

A design in which data are collected from the same subjects repeatedly over a period of time.

• Like making a video instead of a snapshot.
• Helps study changes, trends, and cause-effect relationships.

Types of Longitudinal Studies

• Trend Study; Studies changes in a population over time (different samples each time). Example: Adoption rate of drip irrigation in a state over 10 years.
• Cohort Study; Follows a specific subgroup/cohort (e.g., farmers who adopted HYVs in 2020) over time.
• Panel Study; Studies the same group of respondents repeatedly over time. Example: Following 200 farmers for 5 years to study adoption of organic farming.

5. Case Study Research Design; Meaning: An in-depth investigation of a single unit (individual, group, institution, village, community, organization, event, or program) to understand it in detail. Focuses on “how” and “why” questions.

6. Comparative Research Design; Meaning: Research design that involves systematic comparison of two or more groups, communities, societies, cultures, or programs to identify similarities and differences. Helps in understanding relationships and drawing generalizations.

Characteristics

• Can be cross-national, cross-cultural, or cross-community.
• Can use quantitative (statistical) or qualitative (descriptive) approaches.
• Often used in policy research, education, and extension program evaluations.

7. Mixed Methods Research Design

Meaning: A research design that combines both quantitative and qualitative methods in a single study. Aim: To get a comprehensive understanding of the research problem.