# psych col. test 1 ch. 2

## Terms

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correlation coefficient
a measure of the nature and strength of the relationship between 2 variables
descriptive statistics
use mathematical procedures in an objective, uniform way to to describe different aspects of numerical data
frequency distribution
a summary of how frequently each of the various scores occurs
inferential statistics
use probability and theory to make sound decisions about which results might have occured simply through chance variation
mean
the statisic most often used to describe a set of data. the AVERAGE
measure of central tendancy
a representative score that can be used as an index of the most typical score obtained by a group of participants
measures of variability
statistics that describe the distribution of scores around some measure of central tendancy
median
the central score
mode
the score that occurs more often than any other
normal curve
a bell shaped, symmetrical curve
range
the difference between the highest and lowest values in a frequency distribution
significant difference
probability that the difference might be due to chance is less than 5 in 100
standard deviation
a measure of variability that indicates the average difference between the scores and their mean
behavioral measures
ways to study overt actions and observable and recordable reactions
between-subject designs
randomly assigned groups to either experimental or control conditions
case study
study of one individual or a small group
confounding variable
something which is not purposely introduced into an experiment, and changes a participants behavior and adds confusion to interpretation of the data
control procedures
methods that attempt to hold constant all variables and conditions other than those related to the hypothesis being tested
correlational methods
used to determine to what extent 2 variables , traits, or attributes are related.
positive correlation
+1 : as one set of scores increases, so does the other
negative correlation
-1 :if one set of scores increases, the other decreases
no correlation
0.0 : scores closer to zero mean there is weak or no realtionship between the scores
debriefing
the researcher provides as much information about the study as possible, and makes sure that no one leave feeling upset, confused, or embarrassed
dependant variable
what the experimentor measures
determinism
all events physical, mental, and behavioral, are the result of, or determined by, specific casual factors
double-blind control
both experimentors and subjects are unaware of which participants get which treatment
expectancy effects
whena researcher subtly communicated to the subjects the behaviors they expect to find, producing their dsired reaction
experimental methods
maipulating an independant variable to look for an effect on a dependant variable
independant variable
the factor that the researcher manipulates
observer bias
an error due to the personal motives and expectations of the veiwer
operational definition
standardizes meaning within an experiment , by defining a concept in terms of certain procedures used to measure it or define its prescence
placebo control
placebo effect
occurs when experimental participants change their behavior in the abscence of any experimental manipulation
reliability
the consistency or dependability of behavioral data resulting from psycological testing
representative sample
a representative sample of a population if it matches the overall characteristics of that population
sample
small sample of population
scientific method
a general set of procedures for gathering and interpreting evidence in ways that limit errors and provide dependable conclusions
self-report measures
verbal answers, either written or spoken, to questions the researcher poses
standarization
using unifrom, consistent procedures in all phases of data collection
theory
an organized set of concepts that explain a phenomenon
validity
the info. produced by research accurately measures the psychological quaility it's intended to
variable
any factor that varies in amount or kind
within-subjects design
uses each participant as his or her own control
ex: infant changing emotion based on facial expression

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