Experimental Design in Research

Experimental Design

• Experimental design is a method to test a hypothesis through a series of steps, creating controlled conditions to limit outside interference.
• The purpose is to form a conclusion based on the hypothesis, which can lead to supporting evidence of scientific law and theory.

Variables

• Independent variable: manipulated in an experiment, causing a change in the dependent variable.
• Dependent variable: changes as an effect of the independent variable being changed.
• Control variable: remains unchanged, providing a baseline for comparison.

Scientific Theory and Law

• Scientific theory: explains why things occur the way they do, supported by evidence from repeated experiments.
• Scientific law: a pattern, typically established through an equation, supported by data from repeated experiments.

What Makes a Good Experiment

• A good experiment requires background knowledge, proper equipment, and attention to accuracy and precision.
• Accuracy: how close values collected are to the real value.
• Precision: how close all measurements are to one another.

Experimental Design Process

• Step 1: Define Variables - identify independent, dependent, and control variables.
• Step 2: Formulate a Hypothesis - make an educated guess about the experiment's outcome.
• Step 3: Experimental Design - create a treatment group and a control group.
• Step 4: Assign Subjects - randomly select and assign subjects to groups.
• Step 5: Measure the Dependent Variable - collect data and analyze results.

Example of an Experimental Investigation

• Pharmaceutical company conducts an experiment to test a medication's effectiveness.
• Two groups: treatment group receives the medication, placebo group receives a dummy pill.
• Data collected shows positive results for patients in the treatment group, confirming the medication's effectiveness.