Stats 1045 Vocab 2 Flashcards
Histogram
A graph, often using blocks constructed above class intervals, used to summarize data.
Class Intervals
Ranges of values along the x-axis of a histogram above which blocks are drawn.
Distribution Tables
A listing of the number or percentage of subjects corresponding to each class interval, for all intervals in a data set.
EndPoint
A rule for a histogram that decides into which class intervals subjects are placed if their value is on the boundary between two intervals.
Density Scale
A vertical scale used on histograms defined as ‘percent of subjects per unit.’ (Where the unit is whatever is appropriate for the data.)
Variable
The general term for a characteristic that changes from subject to subject in a study
Quantitative Variables
Variables that are measured by giving a number value (like height, income, age).
Qualitative Variables
Variables that are described by descriptive words or phrases for each subject (like religion, profession, etc.)
DIscret Variables
A quantitative variable with values that can only differ by fixed amounts.
Continuous Variable
A quantitative variable with values that can differ by arbitrarily small amounts.
Cross-Tabulation
A tabular way to control for a confounding factor, where separate distribution tables are made for different values of the confounding factor.
Average list of numbers
The sum of all numbers in a list, divided by how many number entries there are.
Average of a Histogram
The value where the histogram balances when supported at that point.
Meridian of a Histogram
The value for which half of the area of the histogram is to its left, and half to its right.
Cross-Sectional Study
A study when different subjects are compared to each other at one point in time.
Longitudinal Study
A study when the same subjects are followed over time and compared with themselves at different points of time.
Standard Deviation
A measure that represents the spread of a list around its average. More specifically, the r.m.s size of the deviations of the list from the average.
Standard Units
A scale that measures how many standard deviations values in a list are away from the average.
Normal Approximation
The procedure of replacing an original histogram with a normal curve in standard units and using the normal curve to find areas.
Percentiles
Used to summarize histograms, these are values of the variable for which a given percentage of the data is smaller than the value.
Interquartile Range
A measure of spread used on a histogram found by the following subtraction: (75th percentile) - (25th percentile).
Normal Curve
A curve discovered around 1720 by Abraham de Moivre, with a “bell-shaped” histogram that is centered and symmetric about 0
