Statistics Alive! Flashcards
Kurtosis
Height of a distribution is affected by too many or too few middle scores
Leptokurtic
A distribution with many middle scores
Platykurtic
A distribution with few middle scores
Nominal scale
Classifies cases into categories
Ordinal scale
Ranks scores by degree to which they possess the measured trait
Interval scale
Distances between adjacent scores are equal and consistent throughout the scale. (equal-interval scale)
Ratio scale
Interval scale with addition of absolute zero point.
Continuos variable
Variables where values could theoretically fall between adjacent scale units (height, weight, time)
Discrete data
Values that cannot theoretically fall between adjacent scale units (people, photos, etc)
Real limit
Half the scale’s unit (real limit opposed to observed scores)
Frequency table
Lists each observed score along with number of cases falling at each score
Cumulative frequency table
Shows how many scores are at or below (or at or above) any given score
Relative frequency or percentage table
Gives each score’s frequency relative to 100% (values will all be between 0-100).
Cumulative relative frequency or cumulative percentage table
Shows percentage above or below a given score
Grouped frequency table
Frequency table with score intervals. Can show patterns but have to get right size intervals (not too big or small) by guess and check.
Percentile rank table
Indicates percentage of cases falling at or below a given score (not below a given score)
Percentile
The score falling at a particular percentile rank (can be any score on table while percentages will be between 0-100)
Stem-and-leaf display
Hybrid between table and graph with left column indicating first digit of a score and right column indicating every instance of the next digit
Abscissa
X-axis
X-axis
Abscissa
Ordinate
Y-axis
Y-axis
Ordinate
Frequency curve or line graph
Midpoints of data connected by a line without bars
Skewed
Asymmetric distribution with a single peak
Negatively skewed
Many high scores
Positively skewed
Many low scores
Bimodal
A distribution with 2 peaks. Usually an indication that sample contains two distinct subgroups.
Rectangular distribution
Uniform score distribution (like graphing ranks if there are no tied ranks)
Bar graph
Graph appropriate for nominal data with x-axis reflecting categories instead of scores
Pie graph
Circle graph with slices representing percentages