Scientific Method and Hypothesis Testing Notes

Null Hypothesis and P-Value Decision Rules

• Definition of the Null Hypothesis:
  • The null hypothesis serves as a baseline assumption in research stating that no effect, no difference, or no statistical relationship exists between specified variables in a population.
• Decision rules based on the p-value ($P$):
  • $P < 0.05$:
  • Action: Reject the null hypothesis.
  • Statistical Significance: Significant result.
  • Empirical Implication: A statistically meaningful relationship exists between the variables.
  • $P > 0.05$:
  • Action: Accept (fail to reject) the null hypothesis.
  • Statistical Significance: Non-significant result.
  • Empirical Implication: No statistically meaningful relationship exists between the variables.

The Scientific Method

• Primary Function:
  • Used systematically to make objective and reliable empirical observations.
• Sequential Steps of the Scientific Method:
  1. State problem / ask a question: Identify and define the central scientific problem or question under investigation.
  2. Background research: Review existing literature, theoretical frameworks, and prior empirical data relevant to the inquiry.
  3. Construct hypothesis: Formulate a clear, predictive proposition regarding the outcome of the research.
  4. Collect data: Gather empirical data through structured, systematic measurement techniques.
  5. Analyse data & draw conclusion: Evaluate the collected quantitative or qualitative data to draw sound statistical and theoretical conclusions.
  6. Communicate: Report and disseminate findings through scientific channels for peer review, replication, and scientific progress.

Five Characteristics of a Good Hypothesis

• Key criteria required for a robust scientific hypothesis:
  • Logical: Rooted in established theories, preliminary evidence, and sound reasoning.
  • Specific: Clearly specifies the involved variables, target population, and precise nature of the predicted relationship.
  • Testable: Capable of empirical measurement and observational evaluation.
  • Falsifiable: Constructed such that empirical observations could potentially demonstrate it to be untrue.
  • Declarative prediction: Expressed as a direct, definitive predictive statement rather than an open question.

Faulty Methods of Knowledge Acquisition

• Non-scientific methods prone to errors, bias, and unreliability:
  • Authoritative (Authority): Accepting information as fact simply because it originates from an authoritative figure, expert, or institution without demanding empirical proof.
  • Intuition: Relying on gut feelings, spontaneous instincts, or subjective hunches rather than objective analysis.
  • Personal experience: Drawing broad generalizations based solely on individual, subjective anecdotes and personal observations.
  • Tenacity: Persistently holding onto beliefs or traditions out of habit or historical practice, even in the presence of contradictory evidence.

Hypothetical Constructs vs. Operational Definitions

• Conceptual frameworks in scientific research:
  • Hypothetical Constructs (Abstract):
  • Theoretical, non-observable mechanisms, internal states, or abstract attributes (e.g., intelligence, anxiety, motivation) that cannot be directly measured.
  • Operational Definitions (Specific):
  • Concrete, detailed descriptions of exact operational procedures and measurement metrics used to quantify or manipulate a hypothetical construct.