Card Set Information
what are inferences?
logical deductions about event that cant be observed directly
What is descriptive statistics?
methods used to provide a concise dexcription of a collection of quantitaitve information
What is inferential stats?
methods used to make inference from a small group of people to a large group of people
What type of stats is psych testing based upon?
what is measurement?
application of rules for assiging numbers to objects
3 things scales can have- Magnitude
*taller or shorter
3 things scales can have- equal intervals
difference between 2 point net to each other is the same
*such as inches
3 things scales can have- Aboslute zero
it is possible to have none of a paricular queality being measured
*heart rate of a patient dead
types of scales- Nominal scales (2)
-not really scales
-just assigning a random designator numbers to people or things
* hispanic is 1 blacks is 2 white is 0
types of scales- Ordinal scales
-has magnitude but no equal intervals or absolute 0
*expresses magnitude but not by how much
**sam is taller than me. I am taller than Jerry
types of scales- interval scales
have magnitude and equal intervals but not necessiraly absolute 0
types of scales- Ratio scales
has magnitude, equal intervals, and absolute 0
What can nominal data be used for bc of it sfunction?
frequency distirbutions but not in mathematical manipulations
can ordinal data be manipulated?
yes, it can but it is difficult to interpret bc we do not know exactly how much somehting is
with interval data, what cant we do?
make statements about ratios
what is a freq distribution?
summarizes the scores of a group of individuals in terms of how frequently each value was obtained
What is unique about bell shape curve?
-median, mode, and mean are at the same point
what is a postive skew?
more scores are above the mode than below it
what is a negative skew?
means more scores are below the mode than above it
freq dist- What is class interval?
distance between 2 consecutive measruements
*value we decided is meaningful
what question does a percentile rank answer?
what percent of the scaores fall below a particular score
what is percentile a measure of?
what is standard deviation?
an approximation of the average deviation around the mean
what is variance?
variation of the scores around the mean
what is the standard deviation to variance
it is the square root of variance
what are zscores?
distance of a score from the mean in SD with the scores above mean (+) and scores below the mean (-)
WHat do z scores indictate a scores percentile rank?
in terms of the standard deviation of the distribution
What does a zscore of 1.0 indicate?
it is ~84th percentile
what does a zscore of -1.0 indicate?
it is ~16th percentile
which type of IQ test is the most used?
Wechsler IQ test
whats the SD of the wechsler IQ tests? and why?
-SD of 15 bc that was closest to the SD of the scores on the standford binet (calculated by the formula MA/CA
why are the weschler IQ scores so significant?
the are based on populaton stats alone (not calculations of mental age) therfore it shows the individual where they stand compared to others yoour age
can zscores be calculated into percentiles?
yes and vice versa
what is another name for the bell shape curve?
symmetrical binomial probability distribution
McCalls T- what did he change in his system?
-set mean at 50
-SD of 10
what is formula to convert z to t?
what are SAT and GRE calculated by?
what do quartile sytems do?
divide percentage scale into 4 groups
what do decile systems do?
divide the scale into tenths
what are stanines?
divide the scores into standard 9ths
*there are 3 groups in each of lower, middle, high
If there is a standardization sample then...
the test has normative data
what are norm-reference tests?
compare individuals to normative group
*you cna make someone look worse and you look better
what are criterion referenced tests?
compare an individual to a criterion on speific types of skills,tasks, or knwoledge
*making somebody else look bad does not help you
what are criterion referenced tests used for?
mainly for diagnostic purposes