Chapter 1 Scientific Method

Chapter The Process of Life A. Scientific Method The general process of science is said to be characterized by a sequence of stages. (The Scientific Method!) B. Observation 1. Scientists believe nature is orderly and measurable. 2. Science also considers that natural laws do not change with time. 3. Phenomena can therefore be understood from observations.

Let’s Test Your Observation Skills Can you find the 5 differences?

*This principle of science is known as NATURAL CAUSALITY, by its nature it excludes supernatural phenomenon* What are some things that are considered supernatural?

Shows like ghost hunters only “pretend” to be scientific. Why is it impossible to truly study this phenomenon?

The Case of the Slithering Rocks To truly study a mysterious phenomenon, that phenomenon must be repeatable and observable. This rock seemed to move on its own across the desert. The explanation turns out to be a NATURAL ONE.

Inductive reasoning allows a person to combine isolated facts into a cohesive whole, reasoning makes broad generalizations from specific observations. Observation 1: Snakes have tiny pelvic bones Observation 2: Snakes and lizards have similar DNA sequences Observation 3: Snakes appear after lizards in the fossil record. Generalization: Snakes are related to lizards / Snakes evolved from lizards This type of reasoning can result in the development of a HYPOTHESIS.

A hypothesis is a possible explanation for a natural event or a series of observations - to be valid, the hypothesis must be testable. Examples of hypotheses, check those that are valid and can be tested _____Bluebirds sing to attract mates. _____ Bluebird songs are beautiful. _____ Only male bluebirds sing. _____ Sparrows will leave territories where they hear bluebird songs.. _____ Bluebirds hate sparrows.

Create Your Own Hypothesis

Experiments/Further Observations Deductive reasoning involves “if, then” logic that predicts what will happen based on the hypothesis or theory. Involves general RULES to make predictions. Start with a general idea or principle → use that to make predictions. 1. All living things require energy 2. Bacteria are living things 3. Bacteria require energy Prediction: Bacteria deprived of an energy source will die.

One of the most common and useful forms of deductive reasoning is the syllogism. The syllogism is a specific form of argument that has three easy steps. 1. Every X has the characteristic Y. 2. This thing is X. 3. Therefore, this thing has the characteristic Y. 1. Every vertebrate has a backbone 2. Cows are vertebrates. 3. Cows have backbones. Consider the nanobacteria study and how syllogisms were used.

Comparing Inductive and Deductive Reasoning

These graphics shows what kind of reasoning?

Both inductive reasoning and deductive reasoning are used in the scientific process.

FALSIFIABILITY It is important than any statement or hypothesis is falsifiable - if there is no evidence out there that would prove the statement wrong, then there is no point in running any tests.

It is bad science to ask someone to PROVE A NEGATIVE. For example: Prove that ghosts don’t exist. Prove that cell phones don’t cause cancer. Prove that there are no aliens. Prove that telepathy doesn’t exist. The burden of proof lies on the claimant. If you make a claim, then you must be the one to provide evidence for that claim. (It is not on other people to show it to be false.)

E. Data Often the data must be inspected for the probability the data could show a relationship by chance; this is a measure of “significance.” You roll two dice, they both turn up ONEs. This does not fit your prediction that you will only roll a ONE 1 out of 6 times. Is the data significant enough to change your prediction?

What is an anecdote? Anecdotes are singular observations, stories people tell, or things someone might have heard. It is NOT data.

F. Conclusion 1. Whether the data support or reject the hypothesis is the basis for the “conclusion.” - avoid the word "prove" 2. Science findings are reported in scientific journals so results are available to the research community (peer review). 3. The experiments and observations must be repeatable or the research is suspect.

The Importance of Publication After scientists have conducted research, in order for the conclusions to be considered valid, they must publish their findings in a PEER- REVIEWED journal Peer review means that other scientists will look at their experiment, design, data, and conclusions and determine if they think the research is valid. Check out PLOS for a source of open-source, peer reviewed science articles.PLOS JAMA - Journal of the American Medical Association

Let's Recap the Important Points 1. Hypothesis 2. Data Collection 3. Conclusions General Logic Stuff Inductive versus Deductive Reasoning Falsifiability Syllogism Natural Causation

In your own words (or with a graphic) explain the difference between deductive and inductive reasoning.

G. Scientific Theory The ultimate goal is to understand the natural world in scientific theories, and conceptual schemes supported by a broad range of data. Say What? Dissect that sentence....what does it really mean?

2. The terms “principle” and “law” are also used for generally accepted theories. Basic theories of biology are: a. Cell theory b. Biogenesis theory c. Evolution theory d. Gene theory e. Germ Theory Other Theories f. Heliocentric Theory g. Theory of Gravity

Theories can be changed if new evidence presents itself. Much of our understanding of science has changed over the years as our technology has gotten better.

What is the difference between a theory and a law? Theories do not become LAWS. Theories explain sets of data. (WHY) Laws provide general rules for what we expect to happen. (WHAT)

Why isn't creationism considered a theory? Keeping in mind that there is nothing wrong with religious beliefs, things like creationism are not considered scientific because they do not meet the criteria of a scientific theory itself. 1. Creationism -tells- us what happened, and doesn't explain how, when, why or through what mechanism 2. Creationism cannot be proven false - ie, you cannot disprove the existence of a divine creation 3. The nature of creationism means that the primary tenant (divine creation) can never be changed, much for the same reason you can't disprove it. 4. Not based on natural causes (natural causality)

H. A Controlled Study 1. Some investigations are managed where conditions can be kept constant a. A variable is a factor that can cause an observable change b. The experimental variable is the step that is deliberately manipulated (what you changed). c. A dependent variable is what you measure (the results).

Examples of experimental (independent) and dependent variables Question: Does colored light affect plant growth? What is the experimental variable? What is the dependent variable? What variables must be kept constant - or controlled?

Example of a Controlled Study Observation: Babies are born with severe birth defects, mothers of these babies report taking the drug thalidomide during pregnancy for morning sickness. Question: Does thalidomide cause birth defects? Hypothesis: Thalidomide causes birth defects.

Experiment: Control group: Mice not given thalidomide during pregnancy Variable: Mice given thalidomide during pregnancy In this experiment, mice born from both the control and variable group will not have birth defects. This experiment was performed long before thalidomide was marketed and prescribed to pregnant women. Does these mean that the hypothesis is not supported?

What is confirmation bias? What are ways scientists can reduce bias? What is a double blind experiment?

Scientific Method Scenarios - design an experiment (controls, variables, set-up), include ways you could reduce bias in the experiment Identify dependent and independent variables Suggest alternative and null hypothesis. Each table will get their own question to discuss.

A Field Study Example: male bluebirds act aggessively toward other male bluebirds. Question: Will they act aggressively toward birds of a different species? Researchers can place a model of a different bird near the nest to answer the question.

What is Occam's Razor? Ockham's Razor (Occam is the latinized and more common spelling) is a principle proposed by William Ockahm in the 15th century. The original principle stated "Pluralitas non est ponenda sine neccesitate" which translates as "entities should not be multiplied unnecessarily" Simply put: The simplest explanation is usually the correct one.

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