Reasoning in Psychology Using Statistics Psychology 138 Spring

Reasoning in Psychology Using Statistics Psychology 138 Spring 2018

“It’s about almost everything in modern society. ” Bennett, Briggs, Triola (2003), Statistical Reasoning for Everyday life What are Statistics? Reasoning in Psychology Using Statistics • • • World o meters Fun Facts Live Science Why do I have to take stats? Statistical self-defense. Why statistics are fascinating.

“It’s about almost everything in modern society. ” Bennett, Briggs, Triola (2003), Statistical Reasoning for Everyday life • Statistics: tools used to make Data based decisions • Data: numbers with a context What are Statistics? Reasoning in Psychology Using Statistics

Everything after exam 1 • Statistics: tools used to make Data based decisions – Descriptive statistics – Inferential statistics What are Statistics? Reasoning in Psychology Using Statistics

Data What are Statistics? Reasoning in Psychology Using Statistics

• Statistics: tools used to make data based decisions • Data: numbers with a context e. g. , How were numbers measured? Who did they come from? What do they mean? Understanding the context in which the observations are made is critical for both doing statistical analyses as well as interpreting the results. What are Statistics? Reasoning in Psychology Using Statistics

“The world of statistics starts with a question, not with data” Keller 2006, Tao of Statistics • Traditional Knowing: truth or error – Assumes perfect uniformity – Assumes error-free repetitions Tru • Modern Knowing: probabilistic – Assumes variability • Our focus: Scientific Method – Systematic observation (& experimentation) used to explain how and why events occur • Systematic observations constitute data • Statistics are used to describe data & relationships within data Ways of Knowing Reasoning in Psychology Using Statistics “Alternative facts” “Truthiness”

“The world of statistics starts with a question, not with data” Keller 2006, Tao of Statistics • Scientific Method – – – – Ask research question Identify variables and formulate hypotheses Define population Select research methodology Collect data from sample Analyze data Statistics Draw conclusions based on data Repeat The research process Reasoning in Psychology Using Statistics

• Claim: Absence makes the heart grow fonder – But, what about your observation that long distance romances never work out? (Out of sight, out of mind) • How to test the claim scientifically? – What data do we collect? – Who to test? – How do we make our observations? An Example Actual examples: Jiang & Hancock (2013) Reasoning in Psychology Using Statistics ? ?

• What data do we collect? – Identify what we are studying • Variables – Characteristics or conditions that change or have different values for different individuals (or situations) – Independent (explanatory) variables (IV) » Variable that has causal impact » In experiment, variable that is manipulated by researcher – Dependent (response) variable (DV) » Variable observed for changes to assess effect of the manipulation in an experiment » Variables measured in observational research Variables Reasoning in Psychology Using Statistics

• Absence makes the heart grow fonder – What are some potential Independent (explanatory) variables? ? ? • • How long apart? How far apart? How much communication? How “strong” was the relationship to begin with (quasi-independent)? – What are some potential Dependent (response) variables? • Ratings of fondness for partner • Heart rate when seeing a picture of partner • f. MRI of brain when hearing partner’s voice Independent and Dependent Variables Reasoning in Psychology Using Statistics

• What is the level at which the research is focused? – Individuals • Between individuals • Within individuals – Across groups • • Couples Families Cities Ethnic groups • Our example: Absence makes the heart grow fonder – What level(s) could we focus on? Experimental Unit Reasoning in Psychology Using Statistics

• What data do we collect? • Who to test? – Population • Set of all individuals of interest • Typically no access to whole population – Sample • Subset of population data collected from Inferential Statistics: Test sample & generalize results to population as a whole Observing participants (getting data) Reasoning in Psychology Using Statistics

• Absence makes the heart grow fonder • How could we go about testing this? • What data should we collect? • Who to test? • How should we make our observations? – Observational study (Explanatory and Response variables) • Observe & measure variables of interest to find relationships • No attempt to manipulate or influence responses – Experimental methodology (Independent and Dependent variables) • Independent variable manipulated while changes observed in another variable (dependent) • Can establish cause-and-effect relationships • Extensive controls to minimize extraneous sources of variability – Quasi-Experimental methodology • One (or more) of the independent variables is a pre-existing characteristic (e. g. , sex, age, etc. ) Basic Research Methods Reasoning in Psychology Using Statistics

• Learning the basics of SPSS including entering data Today’s Lab Reasoning in Psychology Using Statistics

Two view windows: To switch between the views click on the tabs Brief tour of SPSS Reasoning in Psychology Using Statistics

This is where you specify the details about the variables Each row corresponds to a variable Each column corresponds to a feature of the variables The Variable View Reasoning in Psychology Using Statistics

Each row corresponds to an experimental unit (called “cases” in SPSS lingo) Each column corresponds to a variable So each column in the data view corresponds to a row in the variable view The Data View Reasoning in Psychology Using Statistics