psych stats Flashcards
2 BRANCHES OF STATISTICS
DESCRIPTIVE STATISTICS
and
INFERENTIAL STATISTICS
Use sample data to make general estimates about the larger population
infer, or make an intelligent guess about the population
inferential statistics
Organize, summarize, and communicate a group of numerical observations
Describes large number of data in a single number or in just as few numbers
descriptive statistics
A set of observations drawn
from the population if interest.
sample
Includes all possible
observations about which we’d
like to know something
population
finding something that needs explaining
“ Why are there many problematic personalities in reality shows like Big Brother?
Initial observation
Theory: (1)People with narcissistic personality disorder are more likely to audition
for Big Brother than those without.
(2) Producers will more likely select people with narcissistic personality to
be contestants than those with less extreme personalities
hypothesis testing
Generating theories and testing them
3 types of variables
independent, dependent, confounding
When we collect data we need to decide on two things:
(1) what to measure
(2) how to measure it.
Hypothesis Testing
Data Collection to Test theory
has at least two levels that we either manipulate
or observe to determine its effects on the dependent variable
independent variable
is the outcome variable that we hypothesize to be
related to, or caused by, changes in the independent variable.
dependent variable
is any variable that systematically varies with the
independent variable so that we cannot logically determine which variable
is at work.
A confounding variable
In experimental work the cause, or independent variable, is a
predictor
the effect, or dependent variable, is simply
an outcome
Can take only specific values; no other
values can exist between these numbers
Example:
If we measure the number of times a study
participants gets up early in a particular week,
the only possible values would be whole
numbers. It is reasonable to assume that each
participant could get up early 0 to 7 times in
any given week, but not 1.6 or 5.92 times
discrete observations
Observations of physical, attitudinal, and behavioral characteristics that can on
different values.
Behavioral scientists often study abstract variables such as motivation, self-
esteem and attitudes
variables
2 types of discrete observation
nominal and ordinal variable
2 types of continuous observation
interval and ratio variables
Use for observation that have categories or
names as their values
nominal variables
Are observations that have rankings (i.e. 1st, 2nd , 3rd,
…) as their values
ordinal variables
Can take a full range of values; an infinite number of
potential values exists.
Example:
One person might complete a task in 12.389 seconds.
Someone else might complete it in 14.740 seconds. Limited only by the number of
decimal places we choose to use
CONTINUOUS VARIABLES
Are used for observations that have numbers as their values; the distance between pairs of consecutive number is assume to be equal.
Examples: temperature, IQ, SAT/ACT test scores
INTERVAL VARIABLES
There will often be a discrepancy between the
numbers we use to represent the thing we’re
measuring and the actual value of the thing
we’re measuring (i.e. the value we would get if
we could measure it directly). This discrepancy
is known as
measurement error
Are variables that meet the criteria for interval variables but also have meaningful
zero points.
Examples: weight, height
Ratio variables