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1. Research & the Role of Statistics 2
1. Research & the Role of Statistics 2. Variables & Levels of Measurement
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1. The Structure of Research & The Role of Statistics
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Begin with Broad Questions
Most social research originates from some general problem or question Curious/troubled about some aspect of society
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Begin with Broad Questions
Example: What influences how a child does in school? General question that can’t be adequately addressed by 1 study
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Narrow Down, Focus In Next, we come up with a more specific research question one we can realistically address Here, a review of the scientific literature can serve as a guide Tells you what other researchers have found Gives “bearing” to your research study
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Narrow Down, Focus In Example: What is the relationship between family structure and school performance?
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Narrow Down, Focus In Also can be stated as a causal theory –
an explanation of the relationships b/t phenomena Example: Children with more parental support/guidance will tend to perform better in school.
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Theory Children with more parental support/guidance will tend to perform better in school. Underlined terms are concepts – abstract ideas concepts are ambiguous
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Operationalize operationalize – define a concept in a way that it can be measured
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Operationalize Put another way: turning concepts into…
variables something measurable any trait that can change values from case to case Some concepts easier to operationalize than others Examples: Parental support/guidance # parents in home (1 or 2) School performance GPA (1 to 4)
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Group Exercise: “Operationalization”
Working with the person (or 2) closest to you, come up with variables (something measurable) that could be used as indicators of the following concepts: Healthy lifestyle (of an individual) Economic health of Duluth Success of UMD grads
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Operationalize Hypothesis: derived from theory
statement about a relationship between variables therefore: it is more specific/exact than a theory it is testable
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Operationalize Hypothesis example: Independent variable (x)
Students living in homes with 2 parents/guardians will tend to have higher GPA’s than students from 1-parent households. Independent variable (x) cause (i.e., # of parents) Dependent variable (y) effect or outcome measure (GPA) x y
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Observe Observations allow for hypothesis testing
Science is a systematic method for explaining empirical phenomena Empirical means measurable & observable
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Observe Research methods are the tools used at this stage
How are data to be sampled & gathered? Lab experiment? Survey? Analysis of existing data? Observations produce data
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Analyze Data & Reach Conclusions
Our focus in this class: hypotheses are tested by comparing observations to theoretical predictions Statistical procedures give the ability to tell: whether the data support our hypotheses & by extension, whether our theory is supported
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Analyze Data & Reach Conclusions
Two classes of statistical techniques: Descriptive – used to summarize/organize/ describe data. Example: What is the avg. # of hours per week people spend on cell phones?
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Analyze Data & Reach Conclusions
Two classes of statistical techniques: 2. Inferential – used to generalize findings from a sample to a population Example: polling just a few hundred voters to predict how a presidential election will turn out.
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Generalize Back to Questions
What do the results tell us about our original broader question? Determined by: How theories are operationalized The nature of the observed sample
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2. Variables & Levels of Measurement
Reminder: VARIABLES are any trait that can change values from case to case Attribute – specific value on a variable Example: sex has 2 attributes, male & female Variables ALWAYS should: be exhaustive – variables should consist of all possible values/attributes have mutually exclusive attributes; no case should be able to have 2 attributes simultaneously
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3 Levels of Measurement Nominal – mutually exclusive & exhaustive categories that cannot be meaningfully ordered (e.g., sex, religion, political affiliation) Categories need to be relatively homogenous
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3 Levels of Measurement A B C D *With parents *w/Room- mates *Dorms
Scales for Measuring Students’ Living Arrangements A B C D *With parents *w/Room- mates *Dorms *Away from Home *Apartment *House *Apartmnt *Other
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NOT MUTUALLY EXCLUSIVE
3 Levels of Measurement Scales for Measuring Students’ Living Arrangements A B C D *With parents *w/Room- mates *Dorms *Away from Home *Apartment *House *Apartmnt *Other NOT MUTUALLY EXCLUSIVE
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NOT MUTUALLY EXCLUSIVE
3 Levels of Measurement Scales for Measuring Students’ Living Arrangements A B C D *With parents *w/Room- mates *Dorms *Away from Home *Apartment *House *Apartmnt *Other NOT MUTUALLY EXCLUSIVE NOT EXHAUSTIVE
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NOT MUTUALLY EXCLUSIVE
3 Levels of Measurement Scales for Measuring Students’ Living Arrangements A B C D *With parents *w/Room- mates *Dorms *Away from Home *Apartment *House *Apartmnt *Other NOT MUTUALLY EXCLUSIVE NOT EXHAUSTIVE NOT HOMOGENOUS
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NOT MUTUALLY EXCLUSIVE
3 Levels of Measurement Scales for Measuring Students’ Living Arrangements A B C D *With parents *w/Room- mates *Dorms *Away from Home *Apartment *House *Apartmnt *Other NOT MUTUALLY EXCLUSIVE NOT EXHAUSTIVE NOT HOMOGENOUS O.K.
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3 Levels of Measurement 2. Ordinal – categories can be ranked in addition to being categorized. Example: “I would rather get beat with a lead pipe than attend this class.” 1 = strongly disagree 2 = disagree 3 = neutral 4 = agree 5 = strongly agree
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3 Levels of measurement What’s Wrong with This Question:
How long have you been attending UMD? 1 to 11 months 1 to 2 years 2 to 3 years 3 to 4 years 5 or more years
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3 Levels of measurement 3. Interval-Ratio – categorical units are equal Examples: prison sentence in months, population of Duluth, age This level permits all mathematical operations (e.g., someone who is 34 is twice as old as one 17) Pointy headed issue Interval = no meaningful zero point Ratio = meaningful zero point DOESN’T MATTER ONE BIT FOR DATA ANALYSIS
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Group Exercise Research Hypothesis = Males who experience hair loss become more likely to experience depression. What is the IV? What is the level of measurement for this variable? What is the DV? Operationalize the DV so that it is measured at the nominal, ordinal, and interval/ratio levels.
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