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Section 1: Scientific Methods

Preview

• Bellringer

• Objectives

• The Experimental Method

• Observing

• Hypothesizing and Predicting

• Experimenting

• Organizing and Analyzing Data

Section 1: Scientific Methods

Preview, continued

• Organizing and Analyzing Data

• Drawing Conclusions

• Repeating Experiments

• Communicating Results

• The Correlation Method

• Scientific Habits of Mind

• Imagination and Creativity

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List and describe the steps of the experimental method.

Describe why a good hypothesis is not simply a guess.

Describe the two essential parts of a good experiment.

Describe how scientists study subjects in which experiments are not possible.

Explain the importance of curiosity and imagination in science.

Intuition leads to the flat Earth society and bloodletting; experiments lead men to the moon and microsurgery. - Seth Mnookin

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Science assumes that everything in the universe can be explained, given enough data and experimentation.

All ideas in science are constantly being tested, evaluated, and re-considered.Hypothesis: Testable prediction based on prior knowledge

and observation.Can be supported or rejected based on an experiment.

Theory: Broad explanation based on many experiments and high amounts of data.Examples: Evolution, Plate Tectonics, Big Bang

Discoveries must be reproducible -- designed and recorded such that the results can be repeated by other researchers.

A far different idea is pseudoscience, which appears or claims to be science, but does not follow scientific principles.

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Astrology is an example of a pseudoscience.

The theory that life arose spontaneously from non-living matter persisted from ancient times through the 19th century.

One recipe for life called for dirty garments and husks of wheat to be added to a jar.Wait 21 days, and mice appear!

This belief was based in falsescience.Could it be replicated

consistently?Were any other possible

explanations tested?

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Up through the 20th century, one of the most serious diseases of mankind was smallpox.One of out every 10 children born in France and

Sweden died of smallpox.

The only known “cure” was to contract the disease and recover.

Some inoculated

themselves with fluid and

pus from the sick, hoping to contract a

mild case and survive.

A British physician named Edward Jenner observed that dairymaids living in his hometown often contracted cowpox, a nonlethal disease with similar symptoms to smallpox.

He decided to intentionally infect a young boy with cowpox, then expose him to smallpox.Immunity was successfully conferred to the boy.

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Edward Jenner vaccinating a child with cowpox from a dairymaid. Source: Bettman Archive / Corbis.

A different virus was eventually discovered for use in smallpox vaccinations.Produced much milder

symptoms.Smallpox was declared

eradicated by the World Health Organization in 1980.

The same basic technique has been used to develop vaccines for other illnesses, such as measles, tetanus, chickenpox, whooping cough, and others.

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A monument dedicated to smallpox eradication at the WHO headquarters in Geneva. Source: Wikimedia.

Scientists make most of their discoveries using the experimental method.

This method consists of a series of steps that scientists worldwide use to identify and answer questions.

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All scientific studies, regardless of complexity, follow the same series of steps, called the scientific method.

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Observation: means of gathering information by use of our senses.

Hypothesis: testable idea or explanation that leads to a scientific investigation.

Experiment: set of procedures designed to test the hypothesis.

Correlation Method: When you can’t run an experiment. Much Like cause and effect.

Two Types of Observations:Quantitative: measured or

counted – must contain a number.Qualitative: descriptive that

doesn’t contain a number.

Hypothesis: made after information has been gathered

Parts of an Experiment:Experimental groupControl group Independent variableDependent variable

*Control group: comparison*Exp. Group: tested*IV: manipulated /tested*DV: measured / responding

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Organizing and Analyzing Data:

GraphsData tablesGraphic organizers

Data: Information that a scientist gathers during an experiment.

Conclusion: Is drawn after a scientist analyzes the collected data and is compared to the hypothesis.

Repeat experiment

Communicate Results

The first step is making an observation.Information gathered by noticing specific details of a

phenomenon.Dr. Edward Jenner observed that dairymaids who

contracted cowpox seemed to be protected from the more deadly smallpox.

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The Dairy Maid, 1650s, by Aelbert Cuyp.

Observation is the process of obtaining information by using the senses as well as the information obtained by using the senses.

Observing is the first step of the experimental method.

Observations can take many forms, including descriptions, drawings, photographs, and measurements.

Hypothesizing and Predicting• A hypothesis is a theory or explanation that is based on

observations and that can be tested.

• Forming a hypothesis is the second step of the experimental method.

• A hypothesis is not merely a guess.

• A good hypothesis should make logical sense and follow from what you already know about the situation.

The goal is to be able to explain the observation.A hypothesis, or testable explanation, will be made

based on the scientist’s prior experience and research.Hypotheses are preliminary explanations – they can and are often proven false.

Dr. Jenner’s hypothesis was that exposure to cowpox would grant immunity to smallpox.The hypothesis must be tested.

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A hypothesis is a theory or explanation that is based on observations and that can be tested.

Forming a hypothesis is the second step of the experimental method.

A hypothesis is not merely a guess.A good hypothesis should make

logical sense and follow from

what you already know about

the situation.

Predictions are statements made in advance that express the results that will be obtained from testing a hypothesis if the hypothesis is supported.

A prediction is used to test a hypothesis.

It is important that any hypothesis can be disproved.

Every time a hypothesis is disproved, the number of possible explanations for an observation is reduced.

By eliminating possible explanations a scientist can zero in on the best explanation.

The experiment tests the hypothesis under controlled conditions.A controlled experiment attempts to test a single

variable, while keeping all others constant.The experimental group receives the variable,

while the control group does not.

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Dr. Jenner’s experiment was to inoculate the 8 year-old son of his gardener with fluid from a cowpox pustule, allow the infection to pass, then repeat with a smallpox pustule.

The boy (experimental group) survived 20 inoculations without succumbing to smallpox!

Experiments are procedures that are carried out under controlled conditions to discover, demonstrate, or test a fact, theory, or general truth.

An experiment is performed when questions that arise from observations cannot be answered with additional observations.

Experiments should be designed to pinpoint cause-and-effect relationships.

Good experiments have two essential characteristics: a single variable is tested, and a control is used.

The variable is the factor that changes in an experiment in order to test a hypothesis.

To test for one variable, scientists usually study two groups or situations at one time, with the variable being the only difference between the two groups.

The experimental group is the group in the experiment that is identical to the control group except for one factor and is compared with controls group.

The control group is the group in the experiment that serves as a standards of comparison with another group to which the control group is identical except for one factor.

Organizing and Analyzing Data

• Data is any pieces of information acquired through observation or experimentation.

• Organizing data into tables and graphic illustrations helps scientists analyze the data and explain the data clearly to others.

• Graphs are often used by scientists to display relationships or trends in the data.

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Another significant problem in science is bias; the preference for an experiment to turn out in a certain way.

Bias is not always intentional, but must be controlled by the experimental design.

A blind experiment is conducted so the experimental subjects do not know which is the control and which is the experimental group.Eliminates the “placebo effect”

A double-blind experiment also prevents the actual scientists from knowing which is the control or experimental group.

Data is any pieces of information acquired through observation or experimentation.

Organizing data into tables and graphic illustrations helps scientists analyze the data and explain the data clearly to others.

Graphs are often used by scientists to display relationships or trends in the data.

Bar graphs are useful for comparing the data for several things in one graph.

Graphing the information makes the trends presented in tables easier to see.

Scientists determine the results of their experiment by analyzing their data and comparing the outcome of their experiments with their prediction.

Ideally, this comparison provides the scientist with an obvious conclusion.

The conclusion states whether or not

the hypothesis is supported by the results of the experiment.

But, often the conclusion is not obvious.In these cases, scientists often use mathematical

tools to help them determine whether the differences are meaningful or are just a coincidence.

Scientists often repeat their experiments.The more often an experiment can be repeated with

the same results, in different places and by different people, the more sure scientists become about the reliability of their conclusions.

Scientists look for a large amount of supporting evidence before they accept a hypothesis.

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Accounting for every single variable in a scientific study is nearly impossible. There are many factors that can cause error.

There is where probability comes in. This is the likeliness that a result occurred simply due to random chance.This can be countered by increasing sample size, or the

number of observations used in an experiment or study.Dr. Jenner was able to locate several other parents who

were willing to volunteer their children. He even included his own 11 month-old son in the study.

The results were finally published. Jenner called his technique vaccination after the Latin word for cow “vacca”.

The final step is communication, where the results are published and reviewed by others to check for errors, bias, or other issues.

Dr. Jenner submitted his study to the Royal Society for Medicine, but was told he needed more proof.

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“The Cow-Pock—or—the Wonderful Effects of the New Inoculation!—vide. the Publications of ye Anti-Vaccine Society.”

- Satirical cartoon, 1802.

Scientists publish their results, sometimes in scientific articles, to share what they have learned with other scientists.

Scientific articles include the question the scientist explored, the reasons why the question is

important, background information,

a precise description of how the

work was done, the data collected,

and the scientist’s interpretation

of the data.

When the use of experiments to answer questions is impossible or unethical, scientists test predictions by examining correlations.

Correlation is the linear dependence between two variables.

An example is the relative width of a ring on a tree trunk is a good indicator of the amount of rainfall the tree received in a given year.

Trees produce wide rings in rainy years and narrow rings in dry years.

This method was used to help scientists investigate why the settlers at Roanake Island all died and why many died at the Jamestown Colony.

The Scientists concluded that the settlers may have been the victims of unfortunate timing.

Although correlation studies are useful, they do not necessarily prove cause-and-effect relationships between two variables.

Scientists become more sure about their conclusions only if they find the same correlation in different places and as they continue to eliminate other possible explanations.

There are many examples of published studies or report that have been later found biased, flawed, or outright fraudulent.

These are always detected, eventually, due to the scientific method and peer review.The net effect is loss of time, resources, and public mistrust.

In 1998, Dr. Andrew Wakefield published a study in the British journal The Lancet documenting a link between the MMR vaccine and autism in children. In the following year, over a thousand articles were written about

the possible link, very few by actual experts in the field.Vaccine rates dropped from 92% to 85% in the U.K., with similar

results in other countries.

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Wakefield’s conclusions were found out to be fraudulent and that he had manipulated the data.

Several outbreaks of measles and mumps occurred across the world from 2002-2008.

The United States has seen a similar effect, with vaccination rates below CDC recommendations in several schools.

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According to a Time Magazine survey, 24% of adults place “some trust” in celebrities’ opinions on vaccines.

Good scientists tend to share several key habits of mind, or ways of approaching and thinking about things.

The first habit of mind is curiosity. Good scientists are endlessly curious which drives them to observe and experiment.

The second habit of mind is skepticism. This means that good scientists don’t believe everything that they are told.

The third habit of mind is an openness to new ideas. Good scientists keep an open mind to how the world works.

Another habit of mind is intellectual honesty. A good scientist is willing to recognize the results of an experiment even though it may mean that his or her hypothesis was wrong.

Lastly, good scientists share imagination and creativity.They are not only open to new ideas, but able to conceive

new ideas themselves.They have the ability to see patterns where others do not

or can imagine things that others cannot.This allows for good scientists to expand the boundaries

we know.

An example being when John Snow created a spot map which effectively pinpointed the source of a Cholera epidemic in 1854.

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