Scientific Method, Experimental Analysis, and Data Interpretation
Core concepts
Know the steps of the scientific method: observation, hypothesis, prediction, experiment, data analysis, conclusion. Distinguish independent, dependent, and controlled variables; understand control groups, replication, and sample size. Be able to read tables and graphs, compute means and percentages, identify trends, and distinguish correlation from causation. Know the structure of a scientific report and the meaning of reliability and validity.
Traps in questions
- A hypothesis must be testable and falsifiable.
- The control group differs in the independent variable only.
- Correlation does not imply causation.
- Increasing sample size improves reliability, not necessarily validity.
- Read graph axes carefully - units and scales are common traps.
Worked example / rule of thumb
Experiment: two groups of plants, one with fertilizer (experimental) and one without (control), same light/water/soil. Independent variable = fertilizer; dependent = growth; controlled = light, water, soil. Rule of thumb: change one thing, measure one thing, hold everything else constant. For data questions, state the trend, quantify it, and check for anomalies before concluding.