RESIT research & statistics Flashcards
inference
making decisions and predictions based on the data for answering the statistical question
inferential statistics
methods of making decisions or predictions about a population, based on data obtained from a sample of that population
parameter
numerical summary of the population
categorical variable
if each observation belongs to one of a set of categories
quantitative
if observations on it take numerical values that represent different magnitudes of the variable
discrete quantitative variable
0,1,2,3,4, if its possible values form a set of separate numbers
continuous quantitative variable
if its possible values form an interval
modal category
category with the highest frequency (for a categorical variable)
mode
(for quantitative variable), the numerical value that occurs most frequently
unimodal
data has single mount
bimodal
data has two distinct mounds
median
middle value of the observations when the observations are ordered from smallest to the largest(or other way around)
resistent
if extreme observations have little if any influence on its value
deviation
of an observation x from the mean , the difference between the observation and the sample mean
variance
average of the squared deviations
pth percentile
value such that p percent of the observations fall below or at that value
z-score
for an observation is the number of standard deviations that it falls from the mean. positive z score indicates the observation is above the mean, negative below the mean
empiricism
involves using evidence from the senses or from instruments that assist the senses as the basis for conclusions.
parsimony
theories are supposed to be simple. mid two theories explain the at a equally well, most scientists will opt for the ampler more parsimonious theory
applied research
conducting in real world context
probabilistic
behaviour research findings are not expected to explain all cases all of the time.
availabiliity heuristic
things pop up easily in our mind and to guide our thinking
present bias
name for our failure to consider appropriate comparison groups
confirmation bias
tendency to look only at info that agrees with what we already believe
bias blind spot
the belief that we are uniquely to fall prey to the other biases previously described
reliability
how consistent the results of a measure are
validity
concerns the operationaliztion measuring what is it supposed to measure
internal reliability
a study participant gives a consistent pattern of answers, no matter how the researcher has phrased the question
criterion validity
evaluates whether the measure under consideration is associated with a concrete behavioural outcome that it should be associated with, according to conceptual definition
known groups paradigm
in which researchers see whether scores on the measure can discriminate among two or more groups whose behaviour is already confirmed
convergent validity
the pattern of correlations with measures of theoretically similar or dissimilar constructs
discriminant validity
something should not correlate with measures of construct that are very different
independent trials
if the outcome of any one trial is not affected by the outcome of any other trial
subjective definition of probabilit
the probability of an outcome is defined by personal probability, your degree of belief that the outcome will occur based on available information
sample space
for a random phenomenon, the sample space is the set of all possible outcomes
event
a subset of the sample space
good story bias
people tend to believe convincing stories
deduction
the process of formulating a prediction that follows from your theory
demand characteristics
a participant wants to be a ‘good’ participant
self perception
people do not necessarily have a correct self image
social desireability
participants want to give a good first impression about themselves
primacy effect
the effect of being the first to be observed
recency effects
the effect of being the last to be observed
test retest reliability
strength of an association between test and retest gives an indication of reliability
cronbachs alpha
a measure of internal reliability
external validity
if it can be generalized
covariance
do the two variables go together
temporal precedence
did the cause occur before the effect
cluster sampling
sample random schools, use children in each school
multistage sampling
a random sample of clusters, then a random sample of people within those clusters
stratified random sampling
in which the researcher purposefully selects particular demographic categories or strata, and then randomly selects individuals within each of the categories, proportionate to their assumed membership of the population
oversampling
blood type ab only 0,5 of population, sample extra ab people to precent unreliability
systematic sampling
each fifth person in a class
convenience sampling
a sample that is easily accessible
purposive sampling
search for participants that meet requirements
snowball sampling
start with a couple of subjects, and ask these subjects whether they know more subjects
quota sampling
set a quota (50 law 50 psych students) and select non randomly up until quotas are fulfilled
observer bias
observations are influenced by your expectations
reactivity
people may behave differently when they know that they are being observed
spurious association
association due to a third variable
posttest design
random assignment multiple groups, test the difference after group assignment
repeated measures design
most important within group design, measure twice in each participant, test the difference
discrete variables
not all variables have the same probability
standard deviation
indicates the amount of dispersion in the population
sampling distribution
of a statistic is the probability distribution that specifies probabilities for the possible values the statistic can take
central limit theorem
for any large enough sample, the sampling distribution is approximately normally distributed
confidence interval
interval containing the most believable values for a parameter
confidence level
the probability that this method produces an interval that contains the parameter
type 1 error
false positive, stating that there is an association when there is no association
type 2 error
stating that there is no association when in fact there is one
internal validity
is an indication of a study’s ability to eliminate alternate explanations for the association