Chapter 1 – Scientific Method & Data Reliability

Q&A flashcards covering foundational concepts from the Chapter 1 lecture, including scientific method steps, hypothesis testing, experimental design, data reliability, and differences between laws and theories.

What is the scientific method?

A systematic set of techniques used to observe phenomena, acquire new knowledge, correct previous knowledge, and integrate new information.

Why does correlation alone not prove causation?

Because two events occurring together may be related by coincidence or a confounding variable; only carefully designed experiments with empirical evidence can establish causality.

What is empirical evidence?

Data obtained from carefully designed, controlled, and reproducible experiments used to support or refute a causal claim.

Define qualitative observation.

A descriptive, non-numerical observation (e.g., color, odor, texture) that is inherently subjective.

Define quantitative observation.

A numerical measurement derived from an instrument, allowing objective comparison between experiments.

Why are quantitative observations favored in science?

They provide numerical data that can be compared across studies and whose reliability can be evaluated.

What two questions must every hypothesis satisfy?

Can it be tested? Can it be falsified?

Give an example of an assumption behind a hypothesis.

Assuming cruise-ship bilge water is released into Monterey Bay when proposing it kills starfish.

What is an experiment in scientific research?

A highly controlled procedure designed to generate observations (ideally quantitative) that test a hypothesis.

Why must scientists know the limitations of their measuring tools?

Tool limits affect the precision, accuracy, and interpretation of collected data.

Define confounding variable.

Any factor that can distort or mask the true relationship between two studied variables.

Provide a common example of a confounding variable.

Hot weather increases both ice-cream sales and homicide rates, confounding their apparent relationship.

What is an experimental group?

Subjects intentionally exposed to the condition being tested (e.g., starfish in bilge-water).

What is a control group?

Subjects treated identically except for the tested variable, establishing a baseline for comparison.

Why are placebo groups used in human drug trials?

To eliminate expectation effects as a confounding variable by giving some subjects an inert treatment.

What does statistical significance measure?

The probability that experimental results arose by random chance rather than a real effect.

What information does an R² (coefficient of determination) provide?

How well variations in one variable explain variations in another within a regression analysis.

Define accuracy in measurement.

How close a measured value is to the true or accepted value.

What equation is commonly used to express accuracy?

Percent error = |measured − true| ÷ true × 100 %.

Define precision in terms of reproducibility.

The degree to which repeated measurements yield the same result; quantified with standard deviation.

How is population standard deviation symbolically calculated?

σ = √[Σ(x − x̄)² / N], where x̄ is the mean and N the total number of data points.

Why must a standard-deviation answer include units?

Because the calculation retains the units of the original measured data.

What are significant digits (significant figures)?

All certain digits in a measurement plus the first uncertain (estimated) digit.

Which number is more precise: 12.345 g or 12.34 g, and why?

12.345 g—because it contains more digits conveying certainty plus one estimated digit.

Differentiate a scientific law from a scientific theory.

Law: summarizes repeated observations (what happens). Theory: explains underlying reasons (how and why).

Name the law that states mass is unchanged during chemical reactions.

The Law of Conservation of Mass (Antoine Lavoisier, late 1700s).

Which early theory explained the law of conservation of mass through atoms?

John Dalton’s Atomic Theory.

Why are scientific theories always provisional?

They are revised whenever new, contradictory data emerge.

Describe the iterative nature of the scientific method.

Observation → hypothesis → experiment → data analysis → revise or expand; cycles repeat to refine knowledge.

What two outcomes force a scientist to redesign experiments?

Results are inconclusive OR results conflict with the hypothesis.