Dot Plots and Frequency Tables CCGPS Coordinate Algebra Unit 4 Statistics

Dot Plots Dot plots aid in visualizing the spread of data, frequency of data, and its central tendencies

How to make a DOT PLOT:  Step 1: Label your axis and title your graph. Draw a horizontal line and label it with the variable. Title your graph  Step 2: Scale the axis based on the values of the variable  Step 3:Mark a dot above the number on the horizontal axis corresponding to each data value.

Let’s create a dot plot EXAMPLE #1  Record the data below for each student’s shoe size in the class. Disregard differences in sizing for males and females.

Plot the dots  Much like a box and whisker plot, choose an appropriate scale for the data and create a number line labeling each marker.  Next, record each piece of data using a dot. If a piece of data is repeated, place a dot above the existing plot.

Analyzing the Class data  The spread of data is measured by the range. What is the spread of data?  What is the mode?  What is the center of the data?  Is the distribution skewed or unusual in any way?

Example #2: The number of goals scored by each team in the first round of the California Southern Section Division V high school soccer playoffs is shown in the following table

SHAPES REVIEW  Skewed Right: Most of the data is concentrated to the left of the graph (tail point to the right)  Skewed Left Most of the data is concentrated to the right of the graph (tail points to the left)  Symmetric: The majority of the data is concentrated in the center of the graph (shaped like a bell)

What is the shape of the dot plot?  YES, It is skewed right.

Center and Spread  Center: the value that divides the observations so that about half have smaller values (It is exactly like finding the median)  Spread: the smallest and larges values expressed in an interval (range)

Example #2: Analyze What is the center and spread of the dot plot?  The center is 1 and the spread is 0 through 7

Birthdays Dot Plot EXAMPLE #3  Create a dot plot using the months each person in the class was born.

Birthdays Dot Plot  Choose a scale and label the number line.  Record the data from the table.

Analyzing the Class data  The spread of data is measured by the range. What is the spread of data?  What is the mode?  What is the center of the data?  Is the distribution skewed or unusual in any way?

What is a Frequency Table?  A Frequency table is a table that lists each item in a data set with the number of times it occurs.

Frequency Tables EXAMPLE #4: The frequency of data is measured by how many times a piece of data is repeated. What are the frequencies of each type of snake? Type of Snake Frequency Black Cobra Python Anaconda Rattlesnakes Green Cobra

Construct a Frequency Table (tally sheet) Enter the data value into the 1 st column Data ValueTallyFrequency , 10, 10, 9, 8, 9, 7, 4, 3, 7, 10, 4, 8, 9, 6, 7, 10

Example #5  Choose a scale and label the number line.  Record the data from the table.

Analyzing the Class data  The spread of data is measured by the range. What is the spread of data?  What is the mode?  What is the center of the data?  Is the distribution skewed or unusual in any way?

Classwork Finish the task practice and turn into the bin. You may consult with a partner near you if needed.