The Scientific Method

What are the main steps in experimental design? The experimental design is an organized and logical way to solve problems. Observation Hypothesis Experiment Data Collection Conclusion Retest

What are observations? Observations are gathered through your senses (sight, hearing, touch, hearing, and smell). There are two types of observations: Direct observation: an observation made with the naked eye or with tools like binoculars or microscopes. Indirect observation: observing evidence or signs like footprints or feces.

Bias In science we should always be objective because science is based on evidence and not bias. Bias is disproportionate weight in favor of or against an idea or thing, usually in a way that is closed-minded, prejudicial, or unfair. Biases can be innate or learned. People may develop biases for or against an individual, a group, or a belief.[1] In science and engineering, a bias is a systematic error. Statistical bias results from an unfair sampling of a population, or from an estimation process that does not give accurate results on average. Source: https://en.wikipedia.org/wiki/Bias

What is a hypothesis? Problem question: How does exercise effect heart rate? A hypothesis is a suggested solution to a problem. This solution must be testable and predicts an outcome. They can be written in the form of an “If…, then…, because…” or simply a testable statement. EX: If a person exercises then their heart rate will increase because the body’s muscles will require more oxygen. OR A person’s heart rate will increase when they exercise due to the body’s demand for more oxygen by their muscles.

What is an experiment? Problem question: How does exercise effect heart rate? An experiment is a procedure to test the hypothesis. In order to conduct a reliable experiment, certain parts of the experiment need to remain consistent throughout the experiment. The parts of the experiment that stay the same throughout the experiment are called constants or controlled variables. Example: time spent exercising, type of exercise, test subject and temperature Experiments sometimes need something to compare the results to. This is called a control group or sometimes just a control. Example: resting heart rate compared to exercising heart rate

Problem question: How does exercise effect heart rate? What is an experiment? There are two types of variables in an experiment are: Independent variable: the variable that is purposefully changed or manipulated in an experiment. The factor that you wish to test. Example: exercise vs no exercise Dependent variable: the factor you measure to gather results, or the variable that may change as a result of the independent variable. Example: the different heart rates

What is data? Data is factual information and results of the experiment. There are two types of data: Quantitative data: data consisting of numbers. EX: The heart rate is 80 beats/minute. Qualitative data: data consisting of descriptions, or other data not consisting of numbers. EX: The heart rate is slow or fast.

The Final Steps - Conclusion & Retest Conclusion is the answer to the problem question or hypothesis based on data obtained from the experiment. Example: According to the data collected, exercise causes the heart rate to increase. During rest the heart rate was recorded at 65 bpm. After exercise, the heart rate was recorded at 110 bpm. Retests are done in order to verify the results- experiments must be retested!

Fact, Law, Hypothesis, Theory and Belief: What’s the difference? Theories, laws and facts can start out as a hypothesis when they are first proposed and before they are rigorously tested. A hypothesis is a tentative statement such as “ if A happens then B must happen” that can be tested by direct experiment or observation. Generally, facts are a very elementary statement based on some measurement such as “Humans are about 6 feet tall” or “Water boils at 212 F”. Are some facts more certain than others? Water always boils at 212 F at sea level, but at higher altitudes it boils at lower temperature. So every fact depends on the specific circumstances under which it was measured. Some facts may be false when re-tested with better instruments.

Fact, Law, Hypothesis, Theory and Belief: What’s the difference? A theory is an attempt to explain why certain laws exist and why certain facts are true under specific conditions. Theories are generally accepted by the scientific community as true due to the extensive experimentation and evidence collected that it takes to support a theory. Example: Planetary orbits are elliptical (a Law) because gravity is an inverse-square force (a Law) and matter operates under Newton’s Laws of Motion. Example: Matter is composed of atoms, and this explains how gases behave (a Law), and why we have specific chemical reactions (a Law) and why the periodic table exists (facts).

Fact, Law, Hypothesis, Theory and Belief: What’s the difference? A Law is based on a collection of individual facts about natural phenomena and is an attempt (usually in mathematics) to relate one set of measurable quantities to another (mass, speed, temperature, viscosity). Example: F=ma or V=d/t https://www.youtube.com/watch?v=GyN2RhbhiEU A belief is a statement that is not able to be scientifically tested or measured. Beliefs are not considered within the realm of science. Example: Sunsets are pretty.