L2: Research Methods Flashcards
what is a variable?
- An attribute that assumes different values across people, places and timepoints
- variation in people: individual difference
- variables of interest: thoughts, feelings, and behaviours
what are conceptual variables
- variables are ideas that do not exist physically – are subject to interpretation
- cannot prove that these variables are real
how do you measure conceptual variables
Look for behaviors associated with conceptual variables and measure them instead ie with operational variables
give an example on how we would measure the conceptual variable of intelligence
- Intelligence is defined as ‘the capacity to acquire and apply knowledge and skills’ (conceptual variable)
- Intelligence might be related to other quantities we can measure, such as cognitive abilities
- ie. IQ (intelligence quotient) test
- by taking an IQ test we can get a score of ones intelligence by measuring associated operational definitions like vocab, arithmetic, picture completion, symbol search etc.
How do you define conceptual variables?
Through standardized tests or operational definitions.
Standardized tests: get operational definitions from criteria validated by the academic community
Operational definition: In studies we pick one way to operationalize a conceptual variable
- Defining conceptual variables is a compromise between validity, cost and convenience; there are no perfect measures
what are the cons of self-report questionnaires? (4)
define positive impression management, malingering
- Positive impression management (exaggerating positive traits) and malingering (exaggerating/manufacturing problems)
- Framing (wording of the question matters)
- would you save 200 people or kill 600 - The accuracy
a. Accuracy varies by trait and individual
* High for extroversion, low for anxiety
* Very low in some cases (Narcissistic personality disorder)
* we may say we are always anxious, when we actually have no anxiety etc.
b. Accuracy greater for rating others (but not perfect)
* Halo and horns effect have been observed
* halo = positive traits associated if they are a good person, opposite for horns
* we are better at judging other than ourself
what are the three things we need for a test to be useful?
define Test-retest, inter-rater reliability, construct validity
Test-retest reliability:
Every time we do the test, we get a similar result
Inter-rater reliability:
No matter who is scoring the test, we get a similar result
Construct validity:
The degree to which a construct (i.e. our test) measures what it claims to be measuring. The test should measure what we are looking for.
what is the key distinction between operational definition and construct validity?
Operational definition = what specific test you are applying to measure the conceptual variable
Construct validity = does your test result actually predict the real-world behaviors linked to the conceptual variable (not a given) does it measure what it claims to measure?
what are the measures of central tendency and variability?
Measures of central tendency: mean, median and mode
Measures of variability: range and standard deviation (SD)
what is mean?
the average. perhaps the most useful psychological measure
found by computing the sum of all the scores by the number of cases.
for IQ mean = 100 (in randomly selected pop)
what is the standard deviation
A measure of how much a score in the population typically deviates (±) from the mean
* High SD means a lot of spread around the mean
* Low SD means little spread around the mean
for iq SD= 15
68% are within one SD
what are outliers and how do they relate to the mean?
Outliers: scores very far from the mean
The mean is sensitive to extreme scores (outliers) – particularly if the sample is small
- can change the mean drastically
- Outliers lead to nonrepresentative means and limit the usefulness of means
Identifying SD: varies; generally a score must be at least 2 absolute SD units away from the mean
For IQ (M = 100, SD = 15), outliers might have:
* IQ ≤ 70 (2SD below 100) or IQ ≥ 130 (2SD above 100)
what is the median?
the value separating the higher half of a population from the lower half
- the median is not influenced by extreme scores/outliers
- lowes score could be 0.001 and the highest may be 100000 but the median would not change
- in analysis of salary- the median is often used
- mean is rarely equal to median
what is the mode?
the most frequent occurring value
- no formal analysis of the mode
what is the range?
- the distance between highest and lowest score
- large ranges are possible but rare
- grades could vary 0-100, but 0s and 100s are rare
- thus use standard deviation
- large ranges are misleading, outliers effect
- most scores might be between 40-70, but if one kid gets a 99, the range is 40-99 which is not representative
explain normal distribution curves in psychology
For any variable in a population there will be a distribution.
For each IQ score (x axis), there will be a number of people with that score (y axis)
- a normal distribution (bell curve) can only be found with a randomly selected population
- Symmetrical, bell-shaped (also called Bell Curve)
- 68% of cases between ± 1SD, 95% between ± 2SD
- No skewness
- Limited kurtosis
- Mean = Median = Mode
- most preferred stats are based upon the assumption of a normal distribution