# Reasoning in Psychology Using Statistics Psychology 138 2013.

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Reasoning in PsychologyUsing StatisticsPsychology 1382013

Reasoning in Psychology Using Statistics

Course objectivesScientific reasoning in psychologyimprove your ability conduct and consume psychological researchStatistical Literacythe ability to follow and understand arguments from data"There are three kinds of lies: lies, damned lies, and statistics. Mark Twain

Reasoning in Psychology Using Statistics

What are Statistics?Its about almost everything in modern society.Bennett, Briggs, Triola (2003), Statistical Reasoning for Everyday lifeStatistics are tools, used to make decisions based on dataDescriptive statisticsInferential statisticsData are numbers with a contextHow were the numbers measured, what do they mean?

Reasoning in Psychology Using Statistics

Video reviewMain points from the videoEvery statistical test starts with an appropriate selection of subjectsInferences must be based on more than one observation because of variabilityTwo types of error must be controlled while testing hypothesesA decision is based on two things:The difference between groupsThe variability of the scoresInferential statistics: hypothesis testing rats, robots, and roller skatesWiley (1977)

Reasoning in Psychology Using Statistics

The research processScientific MethodAsk the research questionIdentify variables and formulate the hypothesisDefine your populationSelect a research methodologyCollect your data from a sampleAnalyze your dataDraw conclusions based on your dataRepeat

Producing DataDescribing DataConclusions from Data

Reasoning in Psychology Using Statistics

Producing DataResearch methodsObservation methodsExperimental methodsQuasi-experimentalVariablesTypesOperational definitionsMeasurementsContinuous and discreteScales of measurementSamplingSamples and populationsStatistics and parametersTechniquesBasic ProbabilityExperimental controlReliabilityValidityInternal and externalConfounds & BiasMethodological basics: what are data and how they are produced

Reasoning in Psychology Using Statistics

Describing dataDescriptive Statistics: Statistical tools/procedures to help organize, summarize, and simplify large sets of data (distributions)Describing a single distributionTables and GraphsPropertiesShape, Center, SpreadLocating scores & Transforming distributions (z-scores)The Normal distribution (Unit Normal Table)Describing the relationship between 2 distributionsCorrelation (Pearsons r)

Reasoning in Psychology Using Statistics

Conclusions from DataDistribution of sample means Central Limit TheoremStandard errorError typesType 1 ()Type 2 ()Hypothesis testing1-sample z test1-sample t testRelated samples t-testIndependent samples t-testChi-squared test Correlation and regressionEstimationPoint estimatesConfidence intervalsInferential Statistics: Procedures which allow us to make claims about the population based on sample data

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