Unit 1Assumption vs. InferencePrediction vs. HypothesisExperimentsSlide 5Types of ErrorGraphsSlide 8Slide 9Slide 10Best-Fit LineSlide 12Slide 13Interpolation vs. ExtrapolationSlide 15Slide 16Slide 171Unit 1Methods of Biological SciencesAssumption vs. InferenceAssumption: a statement believed to be true without evidenceInference: a statement believed to be true based on evidence2Prediction vs. HypothesisPrediction: claim made in advance of an outcome•“If, then” statement•No cause providedHypothesis: a causal explanation of a natural phenomenon•“If, then, because”•Must answer WHY something happens•What we test using Experiments (measurements, observations, data, etc.)3Experiments4Variables: a factor that varies in and experimentIndependent variable: manipulated variable; causes the changes observed in the dependent variableDependent variable: responding variable; the one that is measuredExperimentsGroups:Control: group in which the independent variable is eliminated, or set to a standard value•Provides baseline (normal) conditions for comparison to treatment groupsTreatment/ Experimental Groups: groups in which the independent variable is manipulated (changed)•Shows effect of IV on DV5Types of Error1) Sampling Error: Using too small of a sampling size, or a sample that is not diverse enough to representative the whole population or group from which the sample was selected2) Experimental error: procedural fault (Ex: measurement error, calculation error, human goof-up, etc.)6GraphsGraphing Guidelines:1)Meaningful title2)Correctly labeled axes3)Units of measure4)Graph form (scale, graph type, data, etc.)5)Never Extrapolate!78Histogram: Frequency Distribution; Continuous DataBar graphs: Relative Abundance; Categorical DataLine Graphs: Functional Relationship; IV vs. DV Frequency of Shells Based on Length05101520253035404560-64 65-69 70-74 75-79Length of ShellsN u m b e r of S h e llsShell Length vs. Weight55687992455055606570758085909555 60 65 70 75 80 85 90 95Shell Length (mm)Sh e ll W e ig h t (g )Species Specific Clam Shell Weights0102030405060708090100A B C DSpeciesW e ig h t (g)910Best-Fit Line•Best fits the data (follows the data trend/ cluster)•Smooth, but not necessarily straight•Does not extend beyond the data points (Interpolation, NOT extrapolation)1112Best-Fit Line13Interpolation vs. Extrapolation•Interpolation - estimation of an unmeasured quantity based on the trend shown by data points on either side of the unmeasured quantity (estimating a value within the range of measured data)•Extrapolation - estimation of unmeasured quantities based on extending the graph line beyond the measured data (estimating a value outside the range of measured data)•NEVER DO THIS ON A LINE