W10_November5.pptx - Descriptive Inferential Statistics...

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Descriptive & Inferential StatisticsNovember 5
StatisticsStatistics is a collection of techniques that deal with the organization, analysis, and interpretation of dataE.g., Interested in finding out whether people younger than 30 with those older than 50 differ in their opinion of whether entertainment industry should make a serious effort to reduce the amount of sex and violence in its movies, television shows, and music
Descriptive StatisticsDescriptive statistics – Techniques used to summarize, organize, and describe in numbers some aspects of the data set We calculate percentages to represent the sample statisticsE.g., In each sample, we calculate the % of people who respond yes to the question of whether the entertainment industry should make a serious effort to reduce the amount of sex and violence in its movies, television shows, and music We find that 65% of young people and 80% of older people respond yes to the question
Inferential Statistics Inferential statistics – techniques that allow research to draw conclusions or make generalization about the population based on a sample drawn from that population Interpret the difference in sample statistics – Do younger people hold a different attitude about violence in entertainment industry than older people?Is the difference between the two samples statistically significant or is it due to the sampling error?
Descriptive StatisticsDescribing using graphs and numbers the distribution of a variable Remember: Variables take on different values or attributes for different unitsThe unit of analysis refers to things, people, cases or whatever that the variable describesFrequency distributions:Range of values that the variable takes How often it takes each valueDescribe patterns or consistencies in the scoresConvey important information: the minimum, maximum, the most frequently occurring score, the range of scores
Descriptive Statistics: GraphsDifferent types of variables require different types of graphs to display their distributionCategorical variables: Bar or pie chartsQuantitative variables: Histograms
Frequency Distribution of Race/Ethnicity
Bar Chart of Race/Ethnicity Bar charts show the distribution of categorical variablesPercents are often more informative than counts
Pie Chart of Race/Ethnicity Pie charts are popular, but don’t work well when there are more than just a few categories
Histogram of Weight in kgHistograms show how many individuals are in each equal-interval “bin”
Measures of Central TendencyMean (average)Add up all the values Then divide by n(the number of observations)MedianPoint that splits the distribution into two equal halves
When to Use the Mean vs.

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