Presentation on theme: " Easy to make Information is easily understood Each bar represents counts for a category The length of the bar represents the percent of the total."— Presentation transcript:
Easy to make Information is easily understood Each bar represents counts for a category The length of the bar represents the percent of the total that falls into that category
Good for large data sets — at least 15 Give five important pieces of data: median, maximum, minimum, lower and upper quartiles Can be used to compare sets with different number of data points
Box-and-Whisker Plots Math Test Scores median maximum minimum lower quartileupper quartile title number line
Easy to read Each piece represents a percent of the whole Can also calculate the degree of the circle Shows the whole as 100 percent
Circle Graphs title legend percent of total
Kind of a bar graph Easy to make Bars represent an interval of data—not just one number (e.g., 0 to 5) The length of the bar represents the number that falls into that category
Histogram title label for x-axis label for y-axis interval of data for each category
Easy to read Easy to make Best when you have 25 data points or less Shows clusters (groups of points), gaps (large spaces between points), outliers (points much larger or smaller in value) and variability (how the data is spread)
Line Plots Represents 1 cookie title Number line
Organizes bivariate data (two variables) Shows the association between two variables Involves causation and association Shows clusters and outliers Have the independent variable on the x-axis Can only connect points in a time-series
Scatter Plots title Dependent variable y-axis label for y-axis label for x-axis Independent variable x-axis
Easy to make Best with more than 25 values Allows the identification of largest and smallest values, clusters, gaps and outliers Other varieties include back-to-back plots
Mean — A number that represents the middle point, or average. It is the quotient obtained by dividing the sum total of a set of figures by the number of figures.
Mean Health Care Salaries Surgeon$184,150 Home health aides $20,960 Nurses aides $22,960 Dental assistants $30,850 Physical therapists $41,410 Athletic trainers $38,860 The sum of the salaries is $339,190 There are six values. $339,160/6 = $56,531 The mean is $56,531
Median — The value in an ordered set of values that represents the point of which there are as many instances higher as there are lower.
Mean Health Care Salaries Surgeon$184,150 Home health aides $20,960 Nurses aides $22,960 Dental assistants $30,850 Physical therapists $41,410 Athletic trainers $38,860 Put the numbers in order by value: 184,150 41,410 38,860 30,850 22,960 20,960 Find the middle. In this case, the middle is between 38,860 and 30,850. So find the mean of those 38,860 + 30,850 2 $69,720/2 = 34,855 The median is $34,855
Mode — The most frequent value of a set of data. Mean Health Care Salaries Surgeon$184,150 Home health aides $20,960 Nurses aides $22,960 Dental assistants $30,850 Physical therapists $41,410 Athletic trainers $38,860 There is no number that appears most often, therefore: There is no mode.
The mean is $56,531. The median is $34,855. There is no mode. Why are the mean and the median so different if they are both measures of center? The mean is greatly affected by very large or very small numbers. The surgeon’s salary is much greater than the others and that gives us a larger mean.
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