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Measurement
The process of observing and recording the observations that are collected as part of a research effort
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Construct Validity
Are you measuring what you inteded to measure?
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Translation Validity
- Under the umbrella of construct validity
- Focuses on where the operationalization (ie- measure) is a good translation of the construct
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Face Validity
- On it's face, does the operationalization look like a good translation of the construct?
- Does it seem like it fits for this?
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Content Validity
Operationalization is checked against the relevant content domain for the construct
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Criterion-Related Validity
- The performance of your operationalization (ie- measure) is checked against some other criterion
- A prediction of how the operationalization will perform on some other measure based on your theory or construct
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Predictive Validity
- Under criterion-related validity
- Operationalization's ability to predict something it should theoretically be able to predict
- ie- Is your SAT score able to predict your success in college?
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Concurrent Validity
- Under criterion-related validity
- Operationalization's ability to distinguish between groups that it should theoretically bea ble to distinguish between
- ie- Can a measure of depression distinguish between people who are depressed and those who aren't?
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Convergent Validity
- Under criterion-related validity
- Degree to which the operationalization is simuilar to other operationalizations to which it should theoretically be similar
- You'll see this one the most
- ie- Does your measure of depression correlate highly with another measure of depression?
- You want high correlations, but not TOO high :)
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Discriminant Validity
- Under criterion-related validity
- Degree to which the operationalization is not similar to other operationalizations to which it theoretically shouldn't be similar to
- ie- Do you like your therapist & How well you cope in your family... they SHOULDN'T correlate
- You want low correlations
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Inadequate Preoperational Explication of Constructs
- Threat to construct validity
- A really long way to say that people didn't do their jobs. They didn't define what they were doing well enough
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Mono-Operation Bias
- Threat to construct validity
- Pertains to treatment or program
- Used only one version of the treatment or progam
- ie- Trying only one dosage of a drug in a drug trial instead of trying multiple dosages
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Mono-Method Bias
- Threat to construct validity
- Pertains to the measures or outcomes
- Only used one type of measure instead of several
- This is a problem because of accuracy- we need multiple ways to look at results!!
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Hypothesis Guessing
- Threat to construct validity
- People guess the hypothesis and respond to it rather than respond naturally
- This could cause you to mislabel the "cause." You'll attribute effect to treatment rather than good guessing
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Evaluation Apprehension
- Threat to construct validity
- Ppl make themselves look good just because they're in a study
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Experimenter Expectancies
- Threat to construct validity
- Can bias consciously or unconsciously
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Confounding Constructs & Levels of Constructs
- Threat to construct validity
- Conclude that the treatement has no effect when it's only that level of the treatment which has none (might need more or less to see a result)
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Interaction of Different Treatments
- Threat to construct validity
- Ppl get more than 1 treatment
- Labeling issue
- ie- Don't only get tutoring from your program, also get help from family at home
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Interaction of Testing & Treatment
- Threat to construct validity
- Does the testing itself make the groups more sensitive or receptive to the treatment?
- Labeling issue
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Restricted Generalizability Across Constructs
- Threat to construct validity
- You didn't measure your outcomes completely
- You didn't measure some key affected constructs at all
- ie- Viagra was supposed to help with blood pressure
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Reliability
- Consistency or repeatability of a measure
- Getting the same result every time you do the study
- Based on True Score Theory of Measurement
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True Score Theory of Measurement
- Observed score = True ability + Random error
- We never really have the true score!
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Random Error
- Caused by any factors that randomly effect measurement of a variable across the sample
- Things that happen to you on a daily basis but don't change the dynamics of the entire group
- ie- One person is having a bad day the day you administer a depression measure
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Systematic Error
- Caused by factors that systematically affect measurement of a variable across the sample
- Does affect the group average
- ie- Temperature in the room
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Error Component
There's an observed score, a true score, and an error
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Ways to Reduce Measurement Error
- Pilot test the measures
- Train interviewers/observers
- Double-check data
- Statistically adjust for error
- Use multiple measures of the same construct
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Reliabilty Ratio
- Reliabilty ranges from 0 to 1
- It's the percet of the true score that is there
- Shows how much of a true score we have and how much error we have
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Inter-Rater Reliability
- One type of reliability
- Assesses the degree to which different raters/observers give consistent estimates of the same phenomenon about the estimate of the true score
- Percent agreement
- Usually the cut-off for reliability is .80 (about 80% accurate)
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Test-Retest
- One type of reliability
- Correlation btw 2 observations on the same test administered to the same (or similar) sample on 2 diff occasions
- Time btw observations is crucial
- Looking for stability over time
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Parallel-Forms
- One type of reliability
- Correlation btw to observations on parallel forms of a test administered to the same sample
- 2 forms of the "test" can be used independently but it requires that you generate a lot of items (b/c you need to create 2 diff versions)
- Assumes randomly divided halves are equivalent
- Looking for stability across forms
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Internal Consistency
- One type of reliability
- Single test administered to a sample on one occasion
- Assesses the consistency of the results for diff items for the same construct w/in the measure
- Average item-total correlation
- How consistent is the measure inside itself?
- Probably see Conbach's alpha (a) the most (the average of all possible split half correlations)
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Cronbach's Alpha (a)
- Part of internal consistency reliability
- The average of all possible split-half correlations
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Neither Valid nor Reliable
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Relationship of Validity & Reliability
- Both are important, but aren't related
- You can have one without the other
- You want it to be reliable AND valid if you can
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Nominal Level of Measurement
- Numerical values simply name the attribute
- No ordering of values is implied (the number is a place holder, not an indication of how good or bad something is)
- Numerical values are simply "short codes" for longer names
- ie- "1" for male and "2" for female
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Ordinal Level of Measurement
- Attributes can be rank-ordered
- Distances/intervals between attributes have no meaning (you can rank who's higher and who's lower, but you don't know the gap between them)
- ie- Degrees of agreement (strongly agree/agree/neutral...)
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Interval Level of Measurement
- Attributes can be rank-ordered
- Distances/intervals between attributes do have meaning
- ie- Temperature on Fahrenheit scales- if it's 65 today and 75 tomorrow, we can say tomorrow will be 10 degrees warmer
- Ratios don't make sense (80* isn't twice as much as 40*)
- No meaninful Absolute Zero (0* is not the absense of heat)
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Ratio Level of Measurement
- Always a meaninful Absolute zero
- ie- Anything you count or Income in dollars
- Ratios make sense (If you made $2 and I made $4, I made $2 more than you did)
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Survey
- Frequently used method in our field
- Questionnaires & interviews
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Structured Questions
- Dichotomous response format (ie- "yes" or "no")
- Questions based on level of measurement (ie- rank order of preferences)
- Filter or contingency questions (1st question determines qualification to answer the next one)
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Filter or Contingency Questions
- First question determines qualification or necessary experience to answer the next question
- ie- "If no, skip to question 4."
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Double-Barrelled Questions
Questions with more than one response
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Structured Response Formats
- Fill-in-the-Blank
- Check the Answer
- Circle the Answer
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Unstructured Response Formats
- Written text
- ie- "Tell me more about your experience with..."
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Indexes*
- When you combine 2+ variables to reflect a more general construct
- ie- SES Index
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Constructing an Index
- Conceptualization
- Operationalization & Measurement
- Development of rules for calculating the score
- Validation of the index score
- CODV!!
- Consider- does it match what I'm trying to measure??**
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Scaling
- Take qualitative ideas (like willingness to have immigrants in your country) and come up with a way to measure them quantitatively
- Where a lot of error occurs
- Typically yields a single numerical score that represents the construct of interest
- ie- Degree of depression
- Is a process, not a response scale... so it requires more development
- Seen more than indexing
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Purpose of Scaling
- Hypothesis Testing: Is the construct or concept a single dimensional one?
- Exploration: What dimensions underlie some ratings?
- Scoring: For assigning values to responses
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One-Dimensional Constructs
- Higher/Lower
- ie- Age, Height, GPA
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Two-Dimensional Constructs
- Constructs must be related
- ie- Shared activity & communication to measure marital satisfaction
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Likert Scaling
- Unidimensional scaling methods
- Summative scale
- Scaling process, not response-format
- Start w/ large set of items you think all reflect the same construct
- Have a group of judges rate the items on how much they think it relates to the overall concept
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Item-Total Correlations
- Likert scaling
- Throw out items with the total (summed) score across all items
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Internal Consistency
- Likert scaling
- For each item, get the average rating for the top 1/4 of judges and the bottom 1/4
- Better discrimination
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Qualitative Measures
- If it's not numbers, it's qualitative
- Consists of words
- Used to generate new theories/hypotheses, Achieve deep understanding of an issue, Develop detailed stories to describe a phenomenon
- More about understanding something, not proving something
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Quantitative Data
Consists of numbers
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Qualitative Traditions
- A big umbrella, kind of like a theory
- Includes: Ethonography, Phenomenology, Field research, and Grounded theory
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Ethnography
- Qualitative tradition
- Study within the context of a culture
- What only, no interaction
- Concerned with cause & effect
- Sometimes called "naturalistic research"
- Used mostly in anthropological research
- Most common approach is participant observation
- No limits of what will be observed and no real ending point
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Phenomenology*
- Qualitative tradition
- Interested in the phenomenon from the perspective of the participants
- Acknowledge that objectivity is impossible to ascertain and often incl. a section in their report about themselves to acknowledge biases
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Field Research
- Qualitative tradition
- Researcher observes a phenomenon in its natural state (in situ)
- An observation in the environment where they'd normally be
- No implemented controls or experimental conditions to speak of (nature is emphasized over culture here!)
- Only concerned with observing. Not concerned with cause & effect
- Especially useful in observing social phenomena over time
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Grounded Theory
- Qualitative tradition
- To develop a theory, grounded in observation, about a phenomenon of interest
- Build a theory from the ground up or go in with preconceived notions
- Interview changes as you learn things
- Eventually get to a place where you've fully explored the phenomenon & have an idea what's going on
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Qualitative Methods
Think of these not as the umbrella, but as separate umbrellas under tha main umbrella of traditions
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Participant Observation
- Qualitative Method
- Researcher becomes a participant in the culture being observed
- Takes some time
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Direct Observation
- Qualitative Method
- Researcher not a member of the culture being studied but remains unobtrusive
- Just observing- not getting involved
- Don't get as much info as you would if you were participating
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Unstructured Interviewing
- Qualitative Method
- Direct interaction btw. the researcher and respondent
- No set direction- just kind of see where it goes
- There's always a little bit of structure, though, since you're interviewing this person for a reason
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Case Studies
- Qualitative Method
- Intensive study of a specific individual or specific context
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Traditional Criteria for Judging Qualititative Research
- Internal validity
- External validity
- Reliability
- Objectivity
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Alternative Criteria for Judging Qualitative Research
- Credibility
- Transferability
- Dependability
- Confirmability
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Credibility
Est. that the results are credible from the perspective of the participant
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Transferability
Degree to which results can be generalized to other contexts
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Dependability*
- Description by the researcher of changes w/in the context & how these might affect conclusions
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Confirmability
Degree to which others can confirm or corroborate the results
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Indirect Measures
- Unobtrusive measure
- The researcher collects data w/out the participant being aware of it
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Content Analysis
- Unobtrusive measure
- Systematic analysis of text in order to identify patterns
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Secondary Analysis*
When you use data that's already been collected (ie- census report) for new research
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