statistics & research
DESCRIPTION
Statistics & Research. General Background. Importance of Statistics Numbers are powerful Understanding research Conducting research Software SPSS Excel. Variables. Variable – something that can take on more than one value Independent variable – explains or causes - PowerPoint PPT PresentationTRANSCRIPT
Statistics & ResearchStatistics & Research
General BackgroundGeneral Background
Importance of StatisticsImportance of Statistics– Numbers are powerfulNumbers are powerful– Understanding researchUnderstanding research– Conducting researchConducting research
SoftwareSoftware– SPSSSPSS– ExcelExcel
VariablesVariables Variable – something that can Variable – something that can
take on more than one valuetake on more than one value Independent variable – explains Independent variable – explains
or causesor causes Dependent variable explained Dependent variable explained
or effector effect
Examples of VariablesExamples of Variables ExampleExample
– SexSex– Eye colorEye color– Class standingClass standing– AgeAge– Height Height – WeightWeight– Visualization Visualization – SAT-VerbalSAT-Verbal– CuriosityCuriosity
Possible valuesPossible values– Female, maleFemale, male– Blue, brown, greenBlue, brown, green– Fr, soph, jr., sr.Fr, soph, jr., sr.– 6, 19, 25, 70 6, 19, 25, 70
(years)(years)– 60, 72, 84 (inches)60, 72, 84 (inches)– 79, 101, 220 (lbs)79, 101, 220 (lbs)– 1.5, 2.0, 3.0 (secs)1.5, 2.0, 3.0 (secs)– 500, 600 (scores)500, 600 (scores)– 40, 50, 60 (scores)40, 50, 60 (scores)
Population & SamplePopulation & Sample
Population – the complete Population – the complete collection; everyone of interest collection; everyone of interest (adults in U.S.; students at USF)(adults in U.S.; students at USF)
Sample – a subset of the Sample – a subset of the population (students at USF are a population (students at USF are a sample of adults in U.S.; student sample of adults in U.S.; student in this class are a sample of in this class are a sample of students at USF). We usually do students at USF). We usually do research with a sample. Quick research with a sample. Quick and cheap. Using the population and cheap. Using the population is too costly.is too costly.
Parameter & StatisticParameter & Statistic Parameter – a numerical summary of Parameter – a numerical summary of
the population (average age of the population (average age of students at USF if students at USF is students at USF if students at USF is the population).the population).
Statistic – a numerical summary of a Statistic – a numerical summary of a sample (average age of students in sample (average age of students in this class if students at USF is the this class if students at USF is the population).population).
Sample statistics serve 2 purposes:Sample statistics serve 2 purposes:– DescriptiveDescriptive– InferentialInferential
Relations among TermsRelations among Terms
SampleSample
10 people10 peoplePopulationPopulation
all adults in U.S.all adults in U.S.
StatisticStatistic
meanmeanParameterParameter
meanmean
Symbol English Symbol English (Arabic) M or (Arabic) M or
Greek Greek
(mu) (mu) X
Review DefinitionsReview Definitions
PopulationPopulation SampleSample ParameterParameter StatisticStatistic
Types of StudiesTypes of Studies
Design – set of data collection Design – set of data collection proceduresprocedures
Experiment (Experimental study) Experiment (Experimental study) – IV manipulated; often random IV manipulated; often random
assignmentassignment Correlational studyCorrelational study
– IV measured, not manipulatedIV measured, not manipulated
ExperimentExperiment
Independent VariableIndependent Variable– scheduleschedule
Dependent VariableDependent Variable– RphRph
Extraneous Variable(s)Extraneous Variable(s)– Sex of experimenterSex of experimenter– marblemarble
Another ExampleAnother Example
Brannick wants to know if beer Brannick wants to know if beer consumption the night before an exam consumption the night before an exam is related to exam scores the following is related to exam scores the following day. He asks each student taking an day. He asks each student taking an exam the number of beers they had exam the number of beers they had the night before and calculates the the night before and calculates the total score to see relationship.total score to see relationship.
Experimental or correlational?Experimental or correlational? IV? DV? Extraneous (nuisance)?IV? DV? Extraneous (nuisance)?
DefinitionDefinition
The way in which a study is set up The way in which a study is set up and conducted is known as the and conducted is known as the study’s study’s
– ConductConduct– DesignDesign– OperationOperation– TransportTransport
DefinitionDefinition
In an experimental study, the In an experimental study, the ___________ variable is usually ___________ variable is usually deliberately manipulated.deliberately manipulated.
– DependentDependent– ExtraneousExtraneous– IndependentIndependent– NuisanceNuisance
DefinitionDefinition
We want to know about a large group We want to know about a large group of people, but we can only afford to of people, but we can only afford to study a small group of people. In study a small group of people. In statistics, the larger group is called statistics, the larger group is called thethe– FocusFocus– GeneralizationGeneralization– PopulationPopulation– SampleSample