Presentations text content in AP Statistics
AP Statistics CH. 4 Displaying Quantitative Data
By. Jamie Morreale and Thulasi ThiviyanathanSlide2
Histograms plot the bin counts as the height of barsThe bins and the counts in each bin give the distribution of the quantitative variableRelative Frequency Histogram- displays the percentage of cases in each bin instead of the count
What is a Histogram?Slide3
•Used with numerical data•The Bars touch•There are two types–Discrete-bars which are centered over discrete values–Continuous-bars cover a class (interval) of values
How to make a HistogramSlide4
Stem-and-leaf displays- contain all the information found in a histogram and, when carefully drawn, satisfy the area principle and show the distribution. In addition, stem-and-leaf displays preserve the individual data values.
What is a Stem-and-Leaf Display?Slide5
Dotplot is a simple display. It just places a dot along an axis for each case in the dataThey may be displayed vertically or horizontally
What are Dotplots?Slide6
CenterUnusual Points ShapeSpreadUse CUSS when describing a distribution.
Identify if the Histogram has a single, central, or several humps.Modes are humpsUnimodal- a histogram with one main peak Bimodal- histograms with two peaksMultimodal- histograms with three or more peaksUniform- a histogram distribution that is roughly flat
Humps and BumpsSlide8
Identify if the Histogram is Symmetric Tails- are the parts that typically trail off on either side. They can be identified as having long tails or short tails.Skewed- a distribution is skewed if it’s not symmetric and one tail stretches out farther than the other. Skewed Left- when the longer tail stretches to the left Skewed Right- when the longer tail stretches to the right
Outliers- extreme values that don’t appear to belong with the rest of the data. They may be unusual values that deserve further investigation. or just mistakes.
Compare the two graphs on the number of male and female patients
Compare the graphsSlide11
Timeplot- displays data that change over time. Often, successive values are connected with lines to show trends more clearly.
What is a timeplot?Slide12
Don’t make a histogram of a categorical variableDon’t look for shape, center, and spread of a bar chartDon’t use bars in every display- save them for histograms and bar chartsChoose a bin width appropriate to the dataAvoid inconsistent scalesLabel Clearly
What can go Wrong?Slide13
HW Problem #35
According to the data U.S. car milage have a lower center and is skewed to the right. The mode is near 19 mpg. Others have more cars in their category with a mode at 32 mpg and another mode at 22 mpg.
1 l 6 means 16 mpgSlide14
HW Problem #37
2 l 8 means $28 thousand/mW
The graph is skewed to the left and also has some gaps.
According to the timeplot, the cost is generally increasing overtime.Slide15Slide16Slide17Slide18Slide19