Statistics
set of methods and rules for organizing, summarizing, and interpreting data
Population
Parameter is characteristic (usually numerical) of population
Sample
Statistic is characteristic (usually numerical) of a sample
Descriptive
summarizes, organizes and simplifies data
Inferential
uses sample data to make generalization to a population
Sampling error
The discrepancy that exist between a sample statistic and a population parameter; chance discrepancy
Random Sampling
Procedure used to select a subset of a population; Every member has equal chance of being in subset; Subset has greater likelihood of being representative of the population than if nonrandom sampling are used
What makes true experiment?
Manipulate variable (independent variable) --- (dependent variable is measurement); Random sampling; Control extraneous variables / environment
Quasi-experiment
almost" experiment; differential research can't randomly assign people to groups; Conditions are the result of non-manipulated subject variables or time
Theory
Number of statements about underlying mechanisms of behavior
Hypothesis
A testable statement of belief
Construct
A hypothetical concept used in theories (Id, intelligence, frustration)
Operational definition
Describes a set of operations or procedures for measuring a construct; defines construct (variable) in terms of the resulting measurement(Time = seconds, minutes, hours,
Height = inches, meters, feet)
Confounding Variable
Some variable that is linked to independent variable so you don't know If independent or confound lead to the result
Differential research
Groups are formed by subject variables so you can't randomly assign; can lead to faulty conclusions
Time series research
Measure people, give treatment, and measure them again; Can't control 1st time of measuring and 2nd time of measuring (lack ability to control)
Why do we need statistics?
Since sample is available to us, we can use the data from the sample to estimate entire population
Nominal
# represents categories
Ordinal
# represents categories + #'s can be rank ordered (logically placed)
Interval
# represents categories + #'s can be rank ordered (logically placed) + equal intervals between adjacent points (1-2, 2-3, 3-4
Ratio
# represents categories + #'s can be rank ordered (logically placed) + equal intervals between adjacent points (1-2,2-3,3-4) + absolute zero point exists (50 is twice as much as 25, temperature 0?, # of minutes to finish problems, anything negative (-) is
Discrete Data
Number represents exact amount (number of children in family, number of cars in a parking lot); No fractions
Continuous Data
Number in front is best representative given the instrument that you are using; Always add extra decimal place; stop watch, weight scale; Between any 2 numbers, there is always another number (break it down further)