Research Methods

Research Methods

Population

  • Definition: Any complete set of observations (or potential observations).

Real vs. Hypothetical Population

  • Real Population:

    • Definition: All potential observations are available at the time of sampling.

    • Example: If I could put every human being through my memory experiment to determine the exact workings of memory.

    • Application: Gallup polls survey 140 countries around the world on social, political, and economic issues.

  • Hypothetical Population:

    • Definition: All potential observations are not accessible at the time of sampling.

    • Significance: Sampling allows researchers to make generalizations to these hypothetical populations or sub-populations.

Sample

  • Definition: Any subset of observations from a population.

  • Characteristic: Sample sizes are generally smaller than population sizes.

Representative Sampling

  • Purpose: To make good generalizations from our sample back to the population.

  • Requirement: The population must be clearly defined (e.g., Are we discussing all humans, all college students, or Americans?).

  • Ideal Outcome: Our sample should closely match defined population parameters.

    • Example: If 10% of the population identifies as Black, the same percentage should be present in our sample.

Random Sampling

  • Objective: To randomly select participants for the study by drawing from the greater population.

  • Key Point: Each individual in the population has an equal chance of being selected.

Convenience Sampling

  • Definition: Used when complete access to the entire population isn't possible; relies on readily available samples.

    • Example: Undergraduates taking psychology courses at a prestigious urban university.

  • Advantages: Increases research efficiency by allowing quicker study execution.

  • Disadvantages: Decreases generalization capability. However, findings can still generalize if confirmed adequately.

Selection Biases

  • Definition: Occurs when a sample is collected in a way that some members of the intended population are less likely to be included.

  • Types of Bias:

    • Sampling Bias: Unrepresentative sampling methods.

    • Self-Selection Bias: E.g., when the group of individuals has control over their participation.

    • Example: Especially prevalent in online polling or surveys targeting narrow demographics.

Random Assignment

  • Definition: A procedure ensuring each participant has an equal chance of being assigned to any experimental group.

  • Outcome: Generates groups that are similar at the outset of the experiment.

  • Application: All experimental research should utilize random assignment.

How to Randomly Assign Participants

  • Method: Use a physical method to ensure randomness, e.g., flipping a coin, can be an effective strategy.

Validity in Research

  • Questions Addressed: How valid are our results?

  • Types of Validity: External validity and internal validity.

External Validity

  • Definition: The extent to which findings generalize to the population.

  • Factors Influencing External Validity:

    • Random, representative sampling enhances external validity.

    • Question: Can a sample from a hypothetical population exhibit external validity?

    • Answer: Yes, but requires replication.

    • Example: Do results from an intro psychology participant pool generalize to a wider population?

Internal Validity

  • Definition: The extent to which a finding is free from alternative explanations.

  • Consideration: Assess if confounding variables (or third variables) could explain findings instead.

  • Impact of Random Assignment: Leads to enhanced internal validity.

Example of Internal Validity

  • Case Studies:

    • Need for examples illustrating internal validity nuances.

Psychological Methods

  • Significance: Different investigation methods have varied efficiency in acquiring statistical data, validity, and control.

  • Ecological Validity: Refers to the extent findings can be applied to real-world scenarios. Not limited to the specific population but addresses a broader conceptualization.

  • Control: The degree of accuracy in measuring targeted variables through controlled circumstances and environments.

Psychological Methods Overview

  • Case Study:

    • Definition: Intensive investigation and observation of an individual.

    • Pros: Long observation periods enable rapport-building with individuals for in-depth information.

    • Cons: Lack of representativeness, potential observer bias, and low ecological validity. Typically qualitative rather than quantitative.

  • Observational Studies:

    • Definition: Observing individuals' behaviors in natural settings.

    • Pros: Involves numerous participants and avoids artificial laboratory conditions.

    • Cons: Limited to behavioral descriptions, subject to external influences, high ecological validity, but low control. Usually qualitative rather than quantitative.

  • Survey Studies:

    • Definition: Gathering self-reported attitudes, experiences, or demographics from a large number of individuals.

    • Pros: Ability to survey large groups on diverse topics.

    • Cons: Biased responses due to self-reporting, susceptibility to wording effects, medium ecological validity, and medium control. Generally quantitative, with limitations based on correlations.

  • Experimentation:

    • Definition: Manipulating variables in a precise, controlled manner to evaluate one variable's effect on another.

    • Pros: Determines cause-and-effect relationships, researcher control over variables/behaviors.

    • Cons: Ethical concerns and low real-world validity; high control counts against ecological validity. Primarily quantitative.

Ethics in Psychological Research

  • Essential Components of Ethical Research:

    • Voluntary participation of subjects.

    • Informed consent from participants.

    • Prohibition against coercion.

    • Transparency regarding deception.

    • Measures taken to avoid harm (physical or psychological).

    • Maintenance of participant confidentiality.

Protected Populations

  • Definition: Categories of individuals requiring additional ethical considerations during research.

  • Examples of Protected Populations:

    • Children

    • Mentally Disabled individuals

    • Prisoners

    • Pregnant Women (including their unborn fetuses)