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Variables 9/10/2013. Readings Chapter 3 Proposing Explanations, Framing Hypotheses, and Making Comparisons (Pollock) (pp.48-58) Chapter 1 Introduction.

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Presentation on theme: "Variables 9/10/2013. Readings Chapter 3 Proposing Explanations, Framing Hypotheses, and Making Comparisons (Pollock) (pp.48-58) Chapter 1 Introduction."— Presentation transcript:

1 Variables 9/10/2013

2 Readings Chapter 3 Proposing Explanations, Framing Hypotheses, and Making Comparisons (Pollock) (pp.48-58) Chapter 1 Introduction to SPSS (Pollock Workbook)

3 Homework: Due 9/12 Chapter 1 – Question 1 Parts A &B – Question 2 Exam 1 9/19….. (study guide for Thursday)

4 About the Homework It must be turned in during class. It cannot be ed It must appear on the workbook paper (original or a photocopy) You cannot:

5 OPPORTUNITIES TO DISCUSS COURSE CONTENT

6 Office Hours For the Week When – Wednesday 10-12:00 – Thursday 8-12 – And by appointment

7 Course Learning Objectives 1.students will achieve competency in conducting statistical data analysis using the SPSS software program. 2.Students will learn the basics of research design and be able to critically analyze the advantages and disadvantages of different types of design.

8 INDEXES AND SCALES A way of getting content validity

9 Why create a scale/index? To form a composite measure of a complex phenomenon by using two or more items Get at all facets Simplify our data

10 Likert Scale A common way of creating a scale Advantages Disadvantages

11 Guttman Scaling Employs a series of items to produce a score for respondents Ordering questions that become harder to agree with Advantages and disadvantages

12 Guttman Scale

13 SPSS Statistical Package for the Social Sciences

14 What is a statistical package Popular Versions – SPSS – SAS – R – Stata

15 Getting SPSS Don’t Purchase a student version – Limited functions – Limited variables Searching the internet for a “free version” – You might get a virus – The Russians will steal your identity (exception fallacy). Do Use it on the machines on campus- free! Consider purchasing a 6- month license ( download fee)purchasing

16 How to Open Data files Data Files on the Pollack CD GSS2008.SAV- the 2008 General Social Survey Dataset – n=2023 – 301 variables NES2008.SAV- the National Election Study from n=2323 – 302 variables STATES.SAV- aggregate level data for the 50 States. N=50 – 82 Variables WORLD.SAV- aggregate level data for the nations of the world. n=191 – 69 Variables

17 SPSS uses 2 windows Data Editor Window – is used to define and enter your data and to perform statistical procedures. – very spread-sheet like –.sav extension The Output Window – this is where results of statistical tests appear – This opens when you run your first test –.spv extension

18 HOW SPSS WORKS

19 It is like a spreadsheet In Variable View – You define your parameters – Give variables names – Operationalize variables We will not do a lot of this

20 Names and Labels Name how the label appears at the top of the column (like the first row in excel) you cant use dashes, special characters or start with numbers These should represent the variable Labels A longer definition of the variable These describe the actual variable

21 Value Labels This shows how variables are operationalized Value= the numeric value given to a category Label= the attribute of the concept

22 In Data View You type in raw data It looks very much like Excel Rows= cases Columns= Variables

23 How Things are Displayed Edit Options Display names Alphabetical

24 Variables I Like Values and Labels

25 Exiting SPSS If you changed the actual dataset you must save it If you ran any statistics, you must save these as well

26 Variables

27 Measured Concepts We need to operationalize concepts to test hypotheses Concept- Conceptual Definition- Operational- Definition- Operationalization- Variable

28 Four Categories of Variables

29 DISCRETE VARIABLES

30 Nominal Variables Identify, label, and operationalize categories Categories are – Exhaustive – Mutually Exclusive Values are their for quantification only

31 Nominal Examples

32 Ordinal Variables These identify, rank order, label, and operationalize categories The Numbers mean something here Operationalization denotes more or less of an attribute

33 Ordinal Examples

34 Fun While it lasted

35 More Ordinal Fun

36 Health Care

37 Nominal and Ordinal

38 CONTINUOUS VARIABLES

39 What makes them unique The values matter Your variable includes all possible values, not just the one’s that you assign. Name, order, and the distances between values matter.

40 Interval Level Variables The values matter at this level The distances matter The zero is arbitrary

41 Examples of Interval Scales

42 Ratio Variables The Full properties of numbers. Its measurement on Steroids Steroids A zero means the absence of a property Classify, order, set units of distance

43 Examples

44 Energy Use

45 Nominal, Ordinal, Ratio

46 DESCRIPTIVE STATISTICS

47 Descriptive Statistics These simply describe the attributes of a single variable. You cannot test here (you need two variables) Why do them?

48 Categories of Descriptive Statistics Measures of Central Tendency The most common, the middle, the average Mean, Median and Mode Measures of Dispersion How wide is our range of data, how close to the middle are the values distributed Range, Variance, Standard Deviation

49 Frequency Distributions This Provides counts and percentages (relative frequencies) of the values for a given variable Computing a relative Frequency The Cumulative Percent is percentage of observations less than or equal to the category

50 Lets Look at this one again

51 Examples St. Edward’s Data


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