BIO 171 1st Edition Lecture 2Outline of Last Lecture I. Characteristics of Living Organisms II. The Genetic Material: DNAIII. Evolution/The Tree of LifeOutline of Current Lecture II. The Scientific MethodIII. Standard ErrorIV. Experimental Design Current LectureThe Scientific MethodObservations--->Hypothesis--->Predications--->Experiments--->Theory (or back to Hypothesis) -Through observation and experimentation:oObservation= the act of viewing the world around us-Allows us to draw hypotheses oExperimentation= controlled way of asking/answering questions about the world -A hypothesis is a testable, possible explanation for a natural phenomenon used to make predictions and motivate experiments (can never be proven)oA good hypothesis:-Makes predications about observations not yet made or experiments not yet run -Sets up a test for these observations/predictions (which further support hypothesis but do not prove it!)-A prediction is a description of an expected outcome in the test (experimental) group, and in each control group (supports hypothesis)-Correlation vs. CausationoCorrelation does not tell you cause, many things can be correlated but do not cause one another -Ex) consumption of margarine and divorce rate may happen to be correlated with one another, but consumption of margarine is most likely not the cause of divorceThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-A theory is a general explanation of natural phenomena supported by many experimentsand observations oA good theory generates good hypotheses and predicts their outcomes oA theory can also be thought of an evolved hypothesis that is tested to the point where it provides an explanation for observations and experimental results Standard Error -The mean that is typically shown on a graph is an estimate of the real mean because the portion represented is only a sample of the population (not representative of the full pop.)oA larger sample size lowers the standard error (more reliable) oThe higher the variation within the sample population, the less likely it is that thesample mean is close to the true mean Experimental Design -When an experiment predicts a specific hypothesis it is typical to also state a null hypothesis, which predicts no effect. oWhen a null hypothesis is rejected, the hypothesis gains support -Testing hypotheses (controls):oSeveral groups are tested, keeping as many variables the same as possible (for reliability)-Test group= group in which a single variable is changed allowing the researcher to observe its effect -Negative Control group= group that receives no change and therefore no effect is expected -Positive Control group= group receives a variable that has a known effect to ensure the experiment is working properly -Testing hypotheses (variables): oResearchers manipulate the test group differently from the control groups (test group has variables)-Independent variable= manipulation performed y researchers (can choose any variable they desire)-Dependent variable= the effect that is being measured (depends on the independent variable)-A good experimental design consists of:oA large sample size (number of independent data points) which provides a stronger and more reliable estimate oChanges one independent variable at a time oUses control groups (both positive and