The Scientific Method

Goal What is the scientific method? What does the scientific method assume? Does the scientific method work? What is not a scientific argument.

What is science? Science is a tool. Medicine: “I have high cholesterol, what should I do?” –Take cholesterol lowering medication. –Consult your astrologer. –Wish it lower.

The Scientific Method 1.Observe an event. 2.Develop a model (or hypothesis) which makes a prediction. 3.Test the prediction. 4.Observe the result. 5.Revise the hypothesis. 6.Repeat as needed. 7.A successful hypothesis becomes a Scientific Theory. model test

Steps to Solving a Problem (The Scientific Method) 1.Identify the Problem State the problem to be solved or the question to be answered. 2.Collect Information/Research Obtain facts and ideas from books, journals, internet, etc. that provide insight regarding your problem/question. Cite these resources. 3.Form a Hypothesis Based on the information/research you collect, propose a solution or “best guess” that will help guide your experimentation and attempt to answer the proposed problem/question. 4.Test Your Hypothesis – “Experiment” Describe, design, and conduct an experiment that will give you information or data that supports (or not) your hypothesis. 5.Accept or Reject Your Hypothesis – “Analysis” Determine whether your data/results from the experiment supports (or not) your hypothesis; if not, it may be necessary to review your information/research and revise your hypothesis. 6.Report Your Results – “Conclusion” Formulate a conclusion that answers the original question from step one and share the results with the scientific community (or the community at large).

Observations data that are descriptions of qualities such as shape, color, taste, feel, etc… acquired by using your senses Two Types: 1.Objective observation 2.Subjective observation

2 Types of Observations Objective an observation based on fact fact – a piece of information that can be strictly defined and proved true. Subjective an observation based on opinion opinion – a statement that expresses a belief, value, or feeling

Objective or Subjective? Which type of observations should be used in science? Objective observations should be used in science because they are based on facts and the basis of science is to identify the facts!

Objective or Subjective? Science looks like fun today! Subjective Kanye West’s songs sound good! Subjective The counter-tops in class are black! Objective School French fries taste good! Subjective The summer was too short! Subjective There are sixty seconds in a minute! Objective

Inference an explanation that tries to make sense of your observations influenced by your experiences/prior knowledge these explanations may not be true Example Observation: John was breathing heavily as he walked into the classroom. Possible Inferences: 1.He ran to class because he was going to be late 2.He just played basketball in gym

What would you infer? 1.Everyone is closing their book because… 2.Many students buy French fries because… 3.Students arrived to class sweaty because… 4. All of the students are laughing because…

Hypothesis a working explanation or trial answer to a problem an “educated guess” can be written in the form of an “If..., then..., because...” statement is not necessarily proven correct just because data/results from one experiment supports it Example If an individual increases his/her activity level, then their heart rate will increase because the body’s muscles (cells) will require more oxygen to function at a higher level. A faster beating heart will increase blood flow; thus, allowing an increased concentration of oxygen to reach the cells in need.

Data factual information Two Types 1. Quantitative 2. Qualitative

2 Types of Data Quantitative data consisting of numbers Example Heart rate (80 beats/minute) Qualitative data consisting of verbal descriptions or information gathered using scales without numbers Examples Verbal description of heart rate (fast or slow)

Repeated Trials experimental tests done more than once necessary to provide more accurate results; data is averaged together lessens the impact of a chance error on the experimental results Examples In the heart rates lab each participant recorded their heart rates after performing various activities. Each participant’s data (for resting, walking, and running) represents a trial. If five total individuals performed the activities and gathered data, then there were a total of five trials.

Two Types of Variables Independent variables that are purposely changed or manipulated in an experiment the factor that you wish to test usually expressed after the word “if” in the hypothesis could be thought of as the “cause” in a cause and effect relationship Example The activity level (resting, walking, running) Dependent variables that may change as a result of the independent variable the factor you measure to gather results usually expressed after the word “then” in the hypothesis could be thought of as the “effect” in a cause and effect relationship Example The person’s heart rate

Identify the Variables 1.If a student chooses to not study, then they will earn a poor grade. 2.If you drink Gatorade before a soccer game, then you will score more goals. 3.If you increase the mechanical advantage of a pulley system used to move an object, then the input force becomes less. independent variable dependent variable independent variable dependent variable independent variable dependent variable

Control or Control Group a group of subjects in an experiment that are not given any special treatment something that is not manipulated same as the experimental group in every possible way, except for the factor being tested a neutral point of reference for comparison – it allows you to see what changing a variable does by comparing it to not changing anything. Example The resting heart rate represented the baseline heart rate to which any increase in activity level was compared to.

Constants Factors in an experiment (both in the experimental and control groups) that are kept the same and not allowed to change Examples 1.One minute was consistently the amount of time allotted to perform the necessary activity 2.The type of activity performed 3.The stopwatch used during data collection 4.The method used to measure the heart rate

Medical Science Scientific MethodHigh Cholesterol ObservationPatient has high cholesterol Hypothesis (prediction) Certain chemicals may dissolve cholesterol deposits. TestGive 100 patients these chemicals, give 100 patients placebo. Observe resultSame number lower their cholesterol as placebo patients. Revise hypothesis? Try different combo of chemicals. New test?Re-run medical test. Observe results. Scientific TheoryLipitor reduces cholesterol.

Everyday Science Scientific MethodCar Repair ObservationEngine won’t turn over. Hypothesis (prediction)Predict battery is dead. TestReplace battery. Observe resultEngine now turns over. Revise hypothesis?Not needed. New test?Not needed. Scientific TheoryCars won’t work without a fully charged battery.

Everyday Science Scientific MethodMaking Spaghetti Sauce ObservationSpaghetti sauce should be red. Hypothesis (prediction) Try a tomato sauce. TestHeat pot of tomato sauce. Observe resultTaste the sauce - bland. Revise hypothesis?Use tomato sauce and garlic! New test?Add garlic, taste - not so bland. Scientific TheoryThe Final Recipe.

Food Science Throwing something together  Hypothesis Your grandmother’s time-tested recipe  Scientific Theory.

Repeatability A successful theory is repeatable. –By you. –By anyone.

Requirements Objective reality –We all see the same world. Constant Laws of Nature –What happens here, happens there. –What happened yesterday will happen tomorrow. The Cosmos is knowable.

Does it work? Scientific Method is a tool. Does this tool work? –Life expectancy –Mortality rates Are there better tools?

Recap: Theories, Guesses, Laws What does the word “Theory” mean to you? “A conjecture; guess” (Webster’s Dictionary) Does it mean the same to a scientist? “A model which has been born out by repeated tests and observation.” Is a Theory less than a Law? “Evolution is just a theory, it is not a fact.” Do Theories “grow up” to be Laws? “Einstein’s Theory of Relativity”

Theories So: a theory is a highly successful hypothesis. All hypotheses make predictions. All theories make predictions. All theories can be tested. Result: Any scientific theory is subject to change as our ability to make tests, or make observations of a test’s results, improves with time.

Non-scientific Theories Make no predictions Un-testable Can’t be falsified

Non-scientific Theories Car won’t work?  Aliens drained the battery. Spaghetti is bland?  You were meant to eat bland food. Car won’t work?  Gods must be angry. Spaghetti is bland?  At the instant of tasting, tongue is transported to alternate dimension where all flavors are rendered nullified. Happens instantaneously.

Non-scientific Theories The chain of events needed for life to arise is too complicated to have happened by chance, a divine intelligence must therefore have caused life to arise (Intelligent Design). Face on Mars. Viking Orbiter (1976)Mars Global Surveyor (1998)

Falsification A real Scientific Theory tells you what observations are necessary to falsify it. –Not so proponents of: Face on Mars Moon Hoax Intelligent Design Astrologers