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43 Cards in this Set

  • Front
  • Back
random sampling
process of selecting a sample such that the selection of one observation is independent of the selection of any other observation
characteristics of populations
inferential statistics
statistical procedures used to make decisions about a population based from a sample
sampling distribution
hypothetical distribution of the values of a statistic if it were computed repeatedly with similar samples
absolute research
research with the purpose of measuring some phenomenon
comparative research
research that compares the results from two or more groups
scientific method
(steps according to stats)
1. encounter and identify the problem
2. formulate the hypotheses and define variables
3. think through the consequences of the hypotheses
4. design and run the study, collect data, compute stats, test hypotheses
5. draw conclusions
continuous variable
can take on an INFINITE number of values between 2 lengths
discreet variable
finite number of values between two sites
independent variable
values manipulated by the researcher
dependent variable
values measured by the researcher
extraneous variable
not manipulated or measured but they are affecting what you're measuring
Three ways to control the extraneous variables (EV)
1. hold the participants constant on the EV
2. include EV in your design
3. randomize participants to groups
subject bias
subjects change their behavior based on what group they're in
observer bias
researcher changes how they treat participants based on what group they're in
single-blind experiment
subjects do not know what group they're in
double-blind experiment
both the researcher and the subjects do not know which group they're in
causal relationship
studied when there is manipulated variables and controlled EV

*manipulation of the IV is key!
IV -> DV
predictive relationship
a relationship that exists when a researcher can assert only that a change in one variable predicts a change in another variable

PV -> CV
predictor variable
variable in a predictive relationship that is analogous to the independent variable; the researcher predicts from this variable
criterion variable
variable in a predictive relationship that is analogous to the dependent variable; the researcher predicts to this variable
true experiment
research that uses an IV and a DV and controls EV by randomization; causal relationships can be asserted when a true experiment is conducted
observational research
research that can assert only predictive relationships because of the absence of manipulation and randomization
Quasi experimental designs
designs in which the researcher can manipulate the IV but cannot randomly assign participants to groups
Property of measurement:
your data is named and has meaning
Property of measurement:
a meaningful order in the values

ex. 1st place and 2nd place
Property of measurement:
a positive, consistent difference between values
Property of measurement:
true zero
it lacks that variable
ex. temperature does not have this... children - do have this
internal validity

external validity
In a QED:
how valid are your results

generalizability of your results to other groups
Scales of Measurement
1. Nominal
2. Ordinal
3. Interval
4. Ratio
has the characteristic of identity
has identity and order
has identity, order, and distance
has identity, order, distance, and a true-zero
Characteristics of a bar graph
use with qualitative data
bars DON'T touch
categories on X-axis
frequency on Y-axis
Characteristics of a histogram
use with QUANTITATIVE data
bars do touch
intervals on X-axis
frequency on Y-axis
deals with the peak of the distribution: mesokurtic
characteristics of median
depends on frequency of scores and not their actual value
recommended for skewed data
not affected by outliers
characteristics of the mean
balance point in the distribution
sum of the deviations = 0
sum of the squared deviations is a minimum
the sample mean gives you the smallest amount of deviation
sample standard deviation
in original units
as variability increases, increases
= 0 if no variance
indicates relative standing
sample variance
a positive number
= 0 if no variability
as variability inc., inc
in squared units
Least Squares Criterion
E(x - mean)^2 is a minimum
something minus its mean divided by the st. dev.

expressed in terms of st. dev. units
variance of the z scores is 1
st. dev. of z-scores is 1
Z is undefined
the shape of the z-score distribution = x distribution