Variables and Data in Scientific Experiments
When conducting experiments, scientists carefully manage different types of variables. The experimental group is where the action happens—these subjects receive the treatment or manipulation being tested.
The independent variable is what you deliberately change in your experiment—it's what you're testing! The dependent variable is what responds to those changes—it's what you're measuring. Everything else that stays the same across all groups are called constants.
Scientists also use different types of hypotheses in their work:
- A null hypothesis predicts no effect from your independent variable
- An alternative hypothesis predicts your independent variable will cause changes
Data collected in experiments comes in two main forms. Qualitative data describes qualities using words—like "green color," "large size," or "sour taste." Quantitative data uses specific numbers for measurement—like "4 feet long," "6 legs," or "7.2 grams."
💡 Remember This: Qualitative = Qualities (descriptions), Quantitative = Quantities (numbers)