Scientific Investigations and Reports

• Guide to scientific investigations and reports

Question Formulation

• A scientific question is formulated as "How does (IV) affect (DV)?"

Aim/Purpose

• The aim/purpose of an experiment is to investigate how the independent variable affects the dependent variable

Hypothesis

• A hypothesis is a testable statement: "If [IV changes], then [DV changes], because [scientific reasoning]."

Variables

• Independent Variable (IV): The variable changed to observe its effect on another variable
• Dependent Variable (DV): The variable measured or observed in an experiment
• Controlled Variables (CVs): Variables kept constant to ensure a fair test

Fair Test

• A valid experiment changes only one independent variable while keeping all other factors controlled.

Graphing Data

• Correct Axis Labels: IV on the x-axis, DV on the y-axis, including units
• Line of Best Fit (LOBF): Included in the graph, and drawn neatly with a ruler

Observations

• An observation is a statement from direct sensory experience or measurement.
• Example: "After boiling for 2 minutes, a potato is still too hard to eat" is an observation because it is based on direct experience

Types of Data

• Quantitative: Numerical data (counted/measured), e.g., age (20 years), weight (55 kg)
• Qualitative: Data describing qualities or categories, e.g., hair color (black), brand of car (Toyota)
• Discrete: Whole numbers only, e.g., number of pets (2), number of chairs (8)
• Continuous: Measured values, including decimals, e.g., temperature (98.6°F), speed (60.5 mph)

Choosing a Graph

• Line Graph: Used for continuous data (e.g., temperature over time)
• Bar Graph: Used for discrete/categorical data (e.g., number of dice rolls)

Errors and How to Fix

• Reading Error: Misreading numbers on the scale; fix by double-checking and asking for verification
• Parallax Error: Looking at the measurement from the wrong angle; fix by reading at eye level
• Instrumental Error: Faulty or uncalibrated equipment; fix by calibrating and checking before use
• Human Reflex Error: Delay in reaction times; fix by having the same person time it

Errors vs Mistakes

• Errors cannot be entirely avoided, but mistakes can be

First-Hand vs Second-Hand Data

• First-hand data: Collected directly by the researcher
• Second-hand data: Analyzed from someone else's research
• Second-hand data is reliable if: it is not outdated and comes from a credible source.

Reliability vs Validity

• Reliability: The experiment is repeatable, with minimal anomalies and a narrow range of results
• Validity: The experiment ensures that only the independent variable affects the dependent variable with all other variables controlled

Discussion Section of a Report

• A good discussion should include: trends in results, meaning/importance of results, errors identified and how to minimize them, plus a comparison to the hypothesis

Control Group

• The control group does not receive the independent variable change, which serves as a benchmark to compare the effects of the IV.

Report Structure

• Writing a Scientific Report requires the following structure: Title, Question, Aim, Hypothesis, Equipment, Method/Procedure, Results, Discussion, Conclusion, References

Reference Format

• Reference format: Surname, First Initial. (Year). Title in Italics. City, Publisher.

Describing Trends

• Linear Relationship: "As IV increases, DV increases/decreases at a constant rate and is directly proportional."
• Exponential Relationship: "As IV increases, DV increases/decreases to a point where DV becomes constant at _. Graph shows an increasing rate of change as IV increases."