Introduction to the Scientific Method or Can Science Cure the Common Cold?

Introduction to the Scientific Method or Can Science Cure the Common Cold? 1.1 The Process of Science 1.2 Evaluating Scientific Information 1.3 Is There a Cure for the Common Cold?

The Scientific Method The scientific hypothesis => an idea about how things work They must be: • Testable • Falsifiable Many ideas cannot be made into a scientific hypothesis. For example, “It is good to eat peanut butter.”

Generating Hypotheses

Hypotheses need to be tested • Logical is not good enough (and can be biased) • So… use deductive logic => make a prediction about the outcome of an action or the outcome of a test based on observable facts

Deductive Reasoning Deductive reasoning can take the form of “if/then” statements • If vitamin C decreases the risk of catching cold, then people take vitamin C supplements will get fewer colds A Hypothesis can be rejected, but it can never be proven absolutely true. …because there could be other factors (alternative hypotheses)

The Experimental Method Practically, to “prove” a hypothesis, it needs to be tested with good scientific experiments “Truth” in science is what we know and understand based on all available information Scientific hypotheses can be tested by: • Experiments – like hypotheses about colds • Observations of the natural world – like hypotheses about dinosaurs

The Experimental Method • Experimentation has led to the understanding that colds are caused by viruses • Scientists feel this statement is true because: • There are no other reasonable supported hypotheses • This hypothesis has not been rejected • It conforms to a well-accepted scientific principle, the germ theory

The Experimental Method • A scientific theory is an explanation of a set of related observations based on well-supported hypotheses from several different, independent lines of research • The germ theory arose from the accumulated observations of scientists such as Pasteur and Koch

The Experimental Method • Scientists in the 1800s noticed a relationship between disease and specific microorganisms • Many experiments and observations since then all support the idea that certain microorganisms cause human diseases • Because of the germ theory of disease, science believes that colds are caused by viruses, which are microorganisms

Controlled Experiments • Experiments are how scientists gain evidence to objectively support a hypothesis – Or fail to support a hypothesis To be sure that the experiment is unbiased, scientists use controlled experiments

Controlled Experiments Control: • The control is the subject or group that is similar in every way to the experimental subject or group except that the control does not get the experimental treatment

Controlled Experiments • Many people believe that colds can be treated with Echinacea to lessen the duration and severity of the cold symptoms

The Controlled Experiment MUST have Random Assignments to Groups

Controlled Experiments What does this mean? • Since the only difference between the two groups was that the experimental group had Echinacea extract in their tea, that difference should account for the difference in results • But was that the only difference?

Controlled Experiments Other possibilities: Were the participants all the same in… • age? • diet? • stress level? • how often they visited a health care provider? • Do these matter? – Yes

Controlled Experiments • The only way to be sure that the experimental treatment causes the result is to have no other differences between the groups • If this is true, then you have a good controlled experiment

Controlled Experiments • One study alone usually isn’t enough to convince the scientific community • Many more studies of Echinacea were done… • some supported the collected data • some conflicted with the collected data

Minimizing Bias in Experimental Design • What is bias? => Opinions influencing an experiment; • Opinions of researchers • AND opinions of subjects being tested • A good experiment will avoid bias • Using random assignment help to avoid bias and eliminate alternative hypotheses.

Correlations as Experimental Designs • Correlations “relate” two variables (or sets of data) • Correlations may be the best method available • Correlations are limited because they cannot show cause and effect. • Correlations are often done to guide future research

Correlation between stress level and illness

Statistics • Statistics – the science of collecting, organizing, analyzing, and interpreting data in order to make decisions. • Two important branched of statistics are descriptive and inferential. (We just talked about descriptive statistics.) • Inferential statistics are used to make inferences or to summarize data from a sample to a population.

Statistical Error • The idea is to lower statistical error in experiments • Common ways to do this: • Increase sample size • Lower variation • Change experimental design

Linear Regression

Statistical Significance • Biological experiments often have large variation, so how do we know they worked? • We use statistics to determine if the experimental results are statistically significant. • Biology uses 5% of a normal curve to define whether an experiment worked

Evaluating Scientific Sources • Primary – best – peer reviewed • Secondary – okay if the source is reliable (and probably more likely to be used than primary) • Anecdotal – advice given on an individual’s opinions. • Warning – much information is anecdotal but presented as secondary. Diet books are a good example!

Did your research, but you’re still confused… Could mean 2 things: • Reporters are not giving enough information or • The scientists are as confused as you Understand the process of scientific research allows you to make more informed choices about your life.

Science in the News • The internet is a source of scientific information, but be careful with it since anyone can post information • Remember to use valid internet sites when looking for information on the internet • .gov, .edu, etc • Ask yourself, “Where is the data?”

Is There a Cure for the Common Cold? • There is not a cure yet, but prevention methods are known • The best advice wash your hands • Rates of common cold infections are 20% to 30% lower in populations employing effective hand-washing procedures

The Social Context of Science • Who influences the direction of scientific research? • Drug treatments vs. prevention

Introduction to the Scientific Method or Can Science Cure the Common Cold?