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BIOL 1500
Marie Therese Rush

Unit 2 – Science and the Scientific Method The Process of Science Biology- study of living organisms -science is not memorizing what is already known but is using the process of science to discover something new and unknown Scientific method- process of making observations, proposing ideas about how something works, testing those ideas, discardin(modifyingour ideas in response to the test results -allows us to solve problems and answer questions efficiently and effectively Nature of Hypothesis -science is the process of testing hypothesis—statements about how the natural work works Hypothesis- ideas about ‘how things work’ -must be testiable and faslifiable -proposed explanation for one or more observations- something which is viewed once or more times -must be testable- must be possible to evaluate a hypothesis through observations of the measurable universe -A hypothesis can be falsified. -A hypothesis can be proven true. -A hypothesis can be supported. -A hypothesis can be rejected. -Supernatural- not constrained by any laws of nature, and its behavior cannot be predicted using our current understanding of the natural word -must be falsifiable- an observation(s) could potentially prove it false -value judgments, such as, “It is wrong to cheat on an exam” are not scientific because different people have different ideas about right and wrong (to find answers to questions of morality, ethics, or justice, use methods such as philosophy and religion) scientific theory- explanation for set of related Hypothesis Generation-different factors, logical observations that is based on well-supported hypothesis from several different, independent lines of research and creative, influence hypotheses development alternative hypothesis-factors other than the tested hypothesis that may explain observations Hypothesis Tests Inductive reasoning- combining a series of specific observations to discern a general principle -hypothesis often developed via inductive reasoning which consists of making a number of observations and then inferring general principle to explain them Deductive reasoning- involves using general principle to predict expected observation -takes form of “if/than” statements Unit 2 – Science and the Scientific Method -hypothesis are tested via process of deductive reasoning which allows researchers to make specific predictions about expected observations Prediction- concerns the outcome of an action, test, or investigation (result we expect from hypothesis test) -predictions can be tested directly, therefore proven true of false -hypotheses cannot be proven absolutely true—but can be proven beyond reasonable doubt -truth in science- what we know and understand based on all currently available information -always leave opportunity to that what seems true now may someday be proven false -abosolutly proving hypothesis is impossible because there may be other reasons besides the one hypothesized that could lead to predicted result Experimental Method Experiments- sets of actions or observations designed to test specific hypotheses -allows scientists to control conditions that may affect subject of study -manipulating environment allows scientists to eliminate alternative hypotheses that may explain results (systematically) -not all hypothesis can be tested through experimentation (ie. Cause of dinosaurs extinction) and instead are tested based on careful observation of natural work (ie fossils are geological evidence) Data- information collected by scientists during hypothesis testing Variables- any factor that can change in value under different conditions Independent variable- value can be freely changed (horizontal axis—x-axis) Dependent variable- may or may not be influenced by changes in independent variable, but cannot be systematically changed by researchers (vertical axis—y-axis) Controlled Experiments -controlled experiments test hypothesis about the effect of an experimental treatments by comparing a randomly assigned group with a control group Control- not exposed to experimental treatment -controls are individuals that are treated identically to experimental group except for application of treatment -designed to eliminate as many alternative hypothesis as possible -experimental and control groups must be as similar as possible to one another to eliminate alternative hypothesis that could explain the results Random assignment-effective way to minimize differences between groups to designate individuals into either control or experimental groups -each group should be a rough cross-section of the population in study -treat all subjects identically during the course of the experiment to ensure no factor related to interaction between subject and researcher influences the results Placebo-generates one consistent difference between individuals in the two groups Minimizing Bias in Experimental Design -researchers may have strong opinions about the truth of particular hypothesis before they test it which may unfairly influence or bias results of experiment -sources of bias: Unit 2 – Science and the Scientific Method -subject expectation- subjects may consciously or unconsciously model behavior they feel researcher expects from them Blind experiment- subjects are not aware of exactly what they are predicted to experience -observer bias- consistent errors made in measurement and evaluation of results -expecting particular outcome (skew results slightly, cause interaction to lean subjects certain way) -researcher applying treatment should not know which is the experimental or control group until data has been collected and analyzed Double-blind-when both researchers and subjects are unaware of either hypothesis or which is experimental or control group -eliminate effects of human bias on results -results more credible placebo- used for control groups to -can be impractical or unethical -strategies for minimizing bias when designing experiments: -double-blind experiments that keep subjects ad data collectors unaware of which individuals belong to control or experimental group Model Systems: Model systems-used when testing hypotheses that would raise ethical or practical problems when tested on people -mammals are useful as model organisms in medical research as they are closely related to use (have hair, give birth to live young, thus sharing similarities in anatomy and physiology) -vast majority of animals used in biomedical research are rodents (rats, mice, guinea pigs) -some research require animals more similar in human size such as dogs or pigs or share evolutionary relationship such as chimpanzees -model systems allow experimental testing on potential drugs and other therapies before employed on people -lab rats have contributed to better understanding of nearly every serious human health threat including cancer, heart disease, Alzheimer’s disease, AIDS -ethical concerns about the use of animals in research persists Looking for Relationships between factors Correlation- relationship between two variables -can test hypothesis using correlations when controlled experiments on humans are difficult/impossible to perform -use correlational studies to eliminate number of alternative hypotheses by closely examining their subjects -difficult to demonstrate cause-and-effect relationship between two factors simply by showing correlation between them (correlation does not equal causation) -correlations cannot exclude alternative hypotheses and therefore can describe relationship between two factors, but does not strongly imply that one factor causes the other Unit 2 – Science and the Scientific Method Understanding Statistics Statistics-specialized branch of mathematics used to evaluate and compare data Sample-small subgroup -experiment on sample can only estimate true effect because sample is always an imperfect ‘snapshot’ of an entire population Mean-average Statistical tests- can be used to extend results from sample to the entire population -calculates likelihood, given number of people sampled and variation within samples, that the difference between two samples reflects a real, underlying differences between the two populations from which these samples were drawn -help scientists evaluate results of their experiments by determining if results appear to reflect true effect of an experimental treatment on a sample of a population - Statistically significant- results that is very unlikely due to chance of differences between experimental and control samples, so thus likely represents true difference between groups -even when an experimental result is highly significant, hypotheses are tested multiple times before scientists come to consensus on the true effect of a treatment Sampling error- effect of chance on experimental results (difference between sample and population from which it is drawn) Probability- how likely something is to occur -- result due to sampling error Standard error-statistical measure of the amount of variability in sample -used to generate confidence interval-range of values that has high probability (usually 95%) of containing true population mean Unit 2 – Science and the Scientific Method -confidence interval provides way to express how much sampling error is influencing results -small confidence intervals more likely to be statistically significant if hypothesis is true Factors that influence statistical significance: -sample size-number of individuals in the experimental and control groups -if treatment has no effect, small sample size could return results that appear significantly different because of an unusually large and consistent sampling error -if effect of treatment is real but sample size of experiment is small, single experiment may not allow researchers to determine convincingly that their hypotheses has support -more participants there are in a study, the more likely it is that researchers will see a true effect of an experimental treatment even if it is very small -statistically significant result is typically one that has a probability of 5% or less of being due to chance alone -some statistically significant results are ‘false positives’ representing a surprisingly large difference between experimental and control groups that occurred only as result of sampling error (potential error explains why one supportive experiment is not enough to convince all scientists that a particular hypothesis is accurate - Unit 2 – Science and the Scientific Method What statistical tests cannot tell us: -all statistical tests operate with assumption that the experiment was designed and carried out correctly (evaluates the chance of sampling error, not observer error, and statistically significant result is not the last word on an experimentally tested hypothesis Evaluating Scientific Information Primary sources: Primary source- experimental results published in professional journals and peer reviewed by other scientist before publication -written by the researchers themselves and reviewed within the scientific community Secondary source- typically news, books, websites that summarize scientific research presented in primary sources---not peer reviewed and sometimes contain poorly supported information Peer review- other scientists critique results and conclusions of an experiment before it is published, helps increase confidence in scientific information Information from Anecdotes Anecdotal evidence- advice is based on one individuals personal experience -be cautious of basing decisions on anecdotal evidence, which is not equivalent to well-designed scientific research -information based on one persons personal experiance Science in the News -stories in news often don’t contain information about the adequacy of experimental design or controls, number of subjects, or source of scientists funding -when evaluating the quality of research: -consider source of media reports -news organizations more reliable reporters than fact of entertainment tabloids -tv talk shows regularly have guests that promote particular health claim—often present information through anecdotes or incomplete summary of primary literature -internet-anyone can post information -can get highly respected academic and government sources ---to—small companies trying to sell their products—to ---indiviauals who have strong, sometimes completely unsupported ideas -can be difficult to determine reliability of well designed website, and even well-used sites (Wikipedia) may contain erroneous or misleading information Unit 2 – Science and the Scientific Method -when using the web, consider: -choose sites maintained by reputable medical establishments, such as National Institutes of Health (NIH) or May Clinic -it costs money to maintain a website –consider whether the site seems to be promoting a product or agenda –advertisements for specific product should alert you to possible bias -check the date when the website was last updated and see whether the page has been updated since original posting (science and medicine are disciplines that must frequently evaluate new data (reliable websites will be updated often -determine whether unsubstantiated claims are being made (look for references and be suspicious of any studies that are not from peer-reviewed journals When evaluating scientific information from secondary sources: 1. Anecdotal evidence is unreliable means of evaluating infomraitno, nad media sources are variable quality-distinguishing between news stories and advertisments is important when evaluating reliability of information –internet is rich source of information, but users should look for clues to particular websites credibility 2. Stories about science should be carefully evaluated for information on actual study performed, Latin and Greek Roots Bio- means life Deduc-means to reason out, working from facts Induc-means to rely on reason to derive principles-“to cause to happy” Hypo-means under, below, or basis -ology-means study or branch of knowledge about Study Questions: What is the Latin origin of the word science, and what does it mean? -word science is derived from Latin word scientia meaning “to know” -science is a way of knowing or seeking reliable but not infallible knowledge about the real, observable, natural and physical world -science gathers, processes, classifies, analyses, and stores information on anything and everything observable in the universe What are two key features or characteristics of science that help to distinguish science from art? -evidence is required for acceptance (evidence implies that any subject of scientific enquiry is measurable -value judgments (beauty,
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