Part 1 Flashcards
What does the Greek of psycho- mean
Greek root (psyche) means breath, spirit, or soul
What does the Greek of -metrics mean
Greek root (metron) means measure, size, or distance
Name 6 reasons of studying measurements
- minimize subjectivity of judgement: however, in psychology, a lot of the experience is subjective
- make more precise statements
- quantify your observations
- Ensure reliable & valid measures, essential to sound science
- Application: good judgements require good measurement, e.g. applying the DSM-5
- Questionnaires are good to make dependent variables, they also help eliminate error as covariates, controls, or experimental groups
Even if a measurement is never perfect, how can you quantify how wrong you might be?
we need to assess the degree of error
What can introduce error to measuring?
- measurement itself can affect error
2. both participants and researchers can introduce biases to the data
What is the first test you should have done in your life?
APGAR test
What is the apgar test?
it assesses your general level of functioning right after birth
infants are tested on 5 categories, with scores ranging from 0 to 2 for each one
Appearance (colour), Pulse, Grimace, Activity & Respiration
converting observations into quantifiable values (number)
What is empirical thinking?
Assuming our observations are valuable
As opposed to trusting a higher truth, for example, because you may not be able to trust your senses
Who is Francis Galton, what did he contribute
A, if not the, founder of psychometrics
he was perhaps a bit obsessed with observation and measurement
e.g. brush strokes needed to complete a painting, the number of times people fidget during a lecture, developed the first weather map, calculating the degree of association between any two characteristics
For us, his most critical accomplishment was the recognition of individual differences
understanding the ways in which people differ
how do we calculate how large these differences are, and what causes them
What is the difference between traits and states
Trait differences
e.g. extraversion, IQ, depression, anxiety
resistant to change over time
refer to behaviour in general
often easier to measure with questionnaires
State differences
e.g. sleepiness, hunger, depression, anxiety
subject to change over short time periods
refer to behaviour in the moment (i.e. now)
a task tend to measure a state
easy to measure with tasks and questionnaire
Name 2 different types of scaling
- Stimulus-centered scaling: also known as psychophysics (mostly objective), it’s the relation of physical, directly measurable, stimuli to perception
e. g. how little sound is physically possible to hear is objective stimuli, but an subjective experience
2. subject-centered scaling: estimating the subjective presence, absence or degree of a construct most common in psychology, topic of this class we attend to reduce/manage the subjectivity and minimize error from that source
How can questions be turned into measurements
The answers must be converted into numbers depending on the thing we are trying to measure
e.g. False = 0 Not sure = 1 True = 2
What is a benefit of including the numerical value to the questionnaires’ answers
0 = Not at all, 1 = A little, 2 =Moderate, 3 = Severe
some people like to include the scale to give a better idea while evaluating which response they would give
Name the 4 types of scales
- Nominal
- Ordinal
- Interval
- Ratio
Why and how do we introduce numbers in nominal scales
Numbers are assigned as levels only
The numbers could just as easily be words, and using words instead would have no impact on how useful the measurement is to us
e..g when measuring sex, we could assign a value of 0 to women and 1 to men
this would not mean men are better than women, the numeric increase has no inherent value
for analysis purposes, it’s sometimes necessary to code sex this way
Describe the ordinal scale
numbers are not just labels, they also serve to rank individuals. Now we must be using numbers, and in a meaningful way
e.g. an ordinal scaling of height might be assign 1 to the smallest participant, 2 to the next smallest participant, and so on
if we coded women as 0, and men as 1 and claim it’s an ordinal scale, then we are saying men are better in some way
Describe the interval scale
Numbers are labels, and reflect rank, and tell us exactly how much more of something we have now. With an ordinal scale the practical difference between 1 and 2 might be smaller or larger than the practical difference between 2 and 3
e.g. if we go from 28 to 18 celsius we have lost 10 celsius and this is the same degree of change as going from 28 to 38 celsius
true even if from a psychological perspective it’s not perceptually the same
Describe the ratio scale
numbers are labels. and reflect rank, and tell us exactly how much more of something we have, and a score of zero is the smallest possible number
ratio scaled numbers are essentially the same as interval scaled numbers, except that they can’t be negative. Aside from possible interpretation differences, for psychology, ratio numbers are functionally the same as interval numbers
in questionnaires, there usually is never ‘nothing’ as a possibility
starting a scale at 1 instead of 0 can indicate you are acknowledging it is not used as a ratio scale
What do we expect from our distribution of data
we expect a normal distribution
Describe the two different use of the word ‘standard’ in psychometrics
Common units: to compare numbers measure with different scaling methods, we standardize to a common (Z) unit
Common understanding: to compare results across participants, we norm-reference them
“good” performance is a relative term
a raw score on a measurement rarely has much interpretative value on its own
How do we develop good standard scores
- Provide a new measure to a very large sample. It is necessary to achieve a normal distribution of scores, this ensures we have properly capture the range of natural variability.
- Verify the data represent the full range of scores
e. g. if a scale is from 1 to 9, someone must have picked 1 and another 9 to make sure the full range can be captures - Determine the distribution of the scores
- Break sores down into psychologically meaningful groups