Warm Up Develop your own Stem and Leaf Plot with the following temperatures for June

Warm Up Answer:

Frequency is how often something occurs. Example: Sam played football on… Saturday morning Saturday afternoon Sunday afternoon The frequency is: Lesson 5: Frequency

By counting frequencies we can make a frequency distribution table A categorical frequency distribution is used for data that can be placed into specific categories. Categorical Frequency Distribution

Step 1: Make a table with the following columns in order: class, tally, and frequency Creating a Categorical Frequency Distribution

Step 2: Tally the data and place the results in the tally column. Creating a Categorical Frequency Distribution

Step 3: Count the tallies and place the results in the frequency column. Creating a Categorical Frequency Distribution

ClassTallyFrequency Total= Example Categorical Frequency Distribution These are the favorite colors of fifteen 2 nd graders. Red Yellow Green Red Blue Red Green Red Green Yellow Red Blue Green

What about if the categories of data are numbers?

A frequency distribution with classes that are more than one unit in width When the range of the data is large, the data must be grouped into classes Grouped Frequency Distribution

Key Concept

The class width is the range of the class. Can be found by subtracting the lower class limit of one class from the lower class limit of the next class Class Width

Rule #1: Choose the classes You will normally be told how many classes you need Rule #2: Choose Class Width ALWAYS round up to the next whole number Rule #3: Mutually Exclusive This means the class limits cannot overlap or be contained in more than one class. Rules For Grouped Data

Rule #4: Continuous Even if there are no values in a class the class must be included in the frequency distribution. There should be no gaps in a frequency distribution. (with the exception of a class with zero frequency) Rule #5: Exhaustive There should be enough classes to accommodate all of the data Rule #6: Equal Width This avoids a distorted view of the data. Rules For Grouped Data

Step 1: Determine the minimum and maximum values, and how many classes you need Creating a Frequency Distribution

Step 2: Find the class width Class Width = __Range__ # of classes *ALWAYS round up to the next whole number Creating a Frequency Distribution

Step 3: Write your minimum value as your lowest lower limit Class Limits 2 Minimum value Creating a Frequency Distribution

Step 4: Add the class width to your lower limit to find the next lower limit; WRITE BELOW NOT BESIDE! (do all lower limits first) Class Limits 2 Ex: Class width = Go until you have the amount of classes needed (in this case 4) Creating a Frequency Distribution

Step 5: To find each upper limit, subtract one from the next lower limit Class Limits Creating a Frequency Distribution

Step 6: To find last upper limit, add class width to the 2 nd to last upper limit Class Limits Creating a Frequency Distribution

Frequency Distributions Make a frequency distribution table with five classes. Minutes Spent on the Phone Minimum value = Maximum value =

4. Mark a tally | in appropriate class for each data value. Steps to Construct a Frequency Distribution 1. Choose the number of classes 2. Calculate the Class Width 3. Determine All Class Limits For this problem use 5 Find the range = maximum value – minimum. Then divide this by the number of classes. Finally, round up to the next whole number. The lower class limit is the lowest data value that belongs in a class and the upper class limit is the highest. Use the minimum value as the lower class limit in the first class. (67) After all data values are tallied, count the tallies in each class for the class frequencies. ( ) / 5 = 11.6 Round up to 12

Total= Do all lower class limits first. Class Limits Tally f Construct a Frequency Distribution Table Minimum = 67, Maximum = 125 Number of classes = 5 Class width = 12

After conducting a survey of 30 of your classmates, you are left with the following set of data on how many days off each employee has taken this year: Construct a Frequency Table. Assume you want to divide the data into 5 different classes. Try One On Your Own 7, 8, 9, 4, 10, 36, 19, 9, 26, 5, 11, 6, 2, 9, 10, 8, 16, 29, 7, 9, 8, 25, 4, 27, 8, 7, 6, 10, 34, 8

Answer Class LimitsTallyFrequency Total: 30

Frequency Table Worksheet Homework