lecture 17 Flashcards
What do measures attempt to quantify? Example?
Measures attempt to quantify the “true value” of a latent (or hidden) psychological construct
“How extroverted are you?”
the way the construct would be presented to us if we assessed the construct perfectly. ExThe measurement would show exactly what it is.
Are humans stochiastic?
yes
what does stochiastic mean?
functionally stochastic (unpredictable in ways we don’t understand)
Will measures ever be perfectly reliable?
We humans are not perfectly reliable
Thus, measures will never be perfectly reliable
what is measurement error?
measurement error is the difference between what we see and the true value
What is the best we can do?
§ Best we can do is estimate psychological constructs:
combining a quess about true value and measurement error. We will never know what mixture this is. We won’t know how much true value and measurement error there is.
what is the goal around measurement error?
minimize measurement error on average and hopefully maximize true value on average. This limits what we can say about the individual
What example was provided for measurement error?
assume that a person knows for certain their true value is 7.5 out of ten, but the scale you provided them doesn’t go to half numbers, already the measurement instrument is forcing the participant into measurement error. AKA we are getting a half unit of measurement error already.
give examples of sources of measurement error.
“Should I select 7 or 8?”
Response: 7
“Oops, flipped the scale options”
Response: 2 (but meant 8)
many people also flip flop the scale (think small numbers are better)
“Recently hanging out with gregarious friends; I’m comparatively less extroverted,”
Response: 6
“Does extroverted mean extraordinary?”
Response: 3
“I’m bored, choose middle”
Response: 5
Whats the intelligence test example of measurement error?
Intelligence test (IQ)
True value: 100
Sources of measurement error:
Unusually stressful day (score will probably be lower than true value)
Oops, had too much coffee (score will probably be lower than true value)
Oops, had too little coffee (score will probably be lower than true value)
Had to guess on 4 items (any good IQ test would require that you have to guess on some questions otherwise we would have a ceiling effect
Guessed all 4 correct!! Score = 115
Guessed all 4 wrong!!! Score = 85
Guessed 2 correct, 2 wrong. Score = 100
Why is estimation fundamentally limited? but what can we do?
We cannot remove all measurement error
Thus, we never obtain a person’s true value
Best we can do is estimate a person’s true value
While minimizing measurement error
While trying to measure only the intended psychological construct and nothing else
(our intelligence test shouldn’t correlate with cultural backround, first language, gender etc. If this correlates with things we don;t think they should, this reflects measurement error etc. )
are measurement instruments created equal?
Measurement instruments are not created equal! We revise our instruments overtime
Do you need reliability before you get validity?
yes
What is reliability?
What is Reliability: How consistent is a measurement tool?
Is my score similar each time?
Try the color test: www.colorquiz.com
If we can assume that the true value isn’t changing what should happen?
if we can assume that the true value isnt changing, your score should be similar overtime.
What is validity?
Validity: Does the tool measure the psychological construct it claims to?
Is my score representative of something meaningful?
Color test: Does my color score reflect my personality?
What are the 2 measruement goals?
- be consistent (reliability)
- hit the target (validity)
What is the visual analogy of the true value
visual metaphor of a dart board. lightening bolt is a measurement occasion.
tests can be reliable but they are not hitting in the right spot.
if our darts are hitting all over, we know its not at the true value most of the time. We need consistency/ It needs to land in the same place multiple times.
What questions do we need to ask ourselves about mesurement error?
this is derived from the theories we have about the characteristics and the true value. After we have an idea of what the true valie should be, we need to make sure that the scale allows people to assess that true value
What is the nature of the true value?
Does my measurement instrument allow people to express their true value?
If not, estimates will appear to fluctuate even though true value is stable
How does myers briggs type inventory (16 personality types test) encourage measurement error?
this introduces error by pushing people in the middle to either of 2 sides like introverted or extraverted.
Is the big five personality encouraging measurement error?
not so much. this derives theoretically from the idea that intra and extraversion is a mixture and identified by a general trend. It predicts that most people are in between the 2.
on the dart board analogy how would we know we are being reliable and valid?
Reliable: Hitting the same place
Valid: Hitting the target
on the dart board analogy how would we know we are being reliable and not valid?
Reliable: Hitting the same place
Invalid: Off-target
Estimates are biased
on the dart board analogy how would we know we are being not reliable and not valid?
Unreliable: Not hitting the same place
Low validity: No bias, but rarely on target
