Data Management Exam Review
Population - refers to the entire group about which data are being collected
Data - information providing the basis o of a discussion from which conclusions may be drawn; data may often take the form of numbers that can be displayed graphically or in a table
Sample - part of a population selected so as to gain information about the whole population
Frequency - the number of times an event occurs or the number of items in a given category
Stem and leaf plot - a way of organizing and presenting a collection of numbers
Class interval - a category or division used for grouping a set of observations
Bar graph - a visual display of data in which quantities are represented by bars of equal width; typically used with discrete data
Frequency distribution - a set of values of a variable, together with the number of occurrences (frequency) of each value
Histogram - a visual display of data that have been organized into equal class intervals, which appear on the horizontal axis. The heights of the rectangles are proportional to the frequencies they represent. Typically used with continuous data.
Pictograph - a graph that uses pictures or symbols to represent variable quantities
Circle graph (pie graph) - a circle divided into sectors whose areas are proportional to the variables represented
Median - the middle term in a frequency distribution
Box and whisker plot - a horizontal representation of the spread of a distribution
Broken line graph - a graph created by joining data points with line segments
Casual relationship - where one variable directly affects another. Proving a casual relationship is the result of an in-depth study
Scatter plot - a graphical method of showing the joint distribution of two variables in which each point on the graph represents a pair of values
Independent variable - a variable whose value is randomly chosen
Dependent variable - a variable whose value depends on the independent variable
Trend - a pattern of average behaviour that occurs over time
Line of best fit - a straight line graph that best represents a set of data
Correlation - the apparent relation between two variables
Strong linear correlation - occurs if the two variables vary at similar rates
Weak linear correlation - occurs if the two variables vary at rates that are not similar
Positive linear correlation - occurs if the slope of the line of best fit or median-median line is positive
Negative linear correlation - occurs if the slope of the line of best fit or median-median line is negative
Median-median line - a linear model used to fit a line to a data set; the line is fit only to key points calculated using medians
Coefficient of correlation, r - a number from +1 to -1 that gives the strength and direction of the relationship between two variables
Coefficient of determination, r^2 - a number from 0 to +1 that gives the