Modules 7+8

descriptive statistics

descriptive statistics

a set of methods used to summarize and describe the main features of a dataset, such as its central tendency, variability, and distribution

frequency distribution

a summary of how often different scores occur within a sample of scores

frequency polygon

a graph depicting a statistical distribution, made up of lines connecting the peaks of adjacent intervals

histogram

a bar graph depicting a frequency distribution

measures of central tendency

a summary measure that attempts to describe a whole set of data with a single value that represents the middle or center of its distribution

mode

the most frequently occurring scores or scores in a distribution

mean

the average of a distribution (total sum of all scores divided by the number of scores)

median

the middle scores in a distribution

positive skew

the mean is greater than the median

negative skew

the median is greater than the mean

measures of variation

statistics that describe the amount of difference and spread in a data set

range

the difference between the highest and lowest scores in a distribution

standard deviation

a measure of dispersion that shows the spread of scores around the mean

normal curve

an asymmetrical, bell-shaped curve thought to describe the distribution of many types of data

inferential statistics

provides data from a sample that a researcher studies which enables him to make conclusions about the population

statistical significance

the claim that a result from data generated by testing or experimentation is likely to be attributable to a specific cause

p-value

how likely you got the result by chance (probability)

n

symbol for the total number of cases (participants) in an experiment or study

informed consent

participants must be told enough information to choose whether or not they want to participate

protection from harm

all psychologists have the ethical obligation to ensure that their participants are safe from psychological and physiological harm

confidentiality

the obligation of a research group to keep participant information private

debriefing

the process of explaining the research being done to the participants after the experiment

institutional review board

federally-mandated, locally-administered groups charged with evaluating risks and benefits of human participant research at their institution