Assign # 4 - Organizing Data (Frequency Tables and...

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Organizing Data (Frequency Tables and Histograms) Once we have identified our objects of interest, specified the variable we wish to measure or observe, and collected our data using an appropriate sampling method, it is then time to organize and display our data. If we are working with a large set of quantitative data, a frequency table and histogram are a good way to organize and display the data. A frequency table allows us to place the data into smaller intervals or “classes” and the histogram will allow us to make comparisons among these classes. Histograms are much like bar chart, except a histogram is based on intervals. We are going to create a frequency table, find the relative frequency of each class and then use the organized data to create a histogram in order to display the data. Our frequency table will contain six columns: Class Limits, Class Boundaries, Tally, Frequency, Class Midpoint, and Relative Frequency. Not all frequency tables must contain all six of these columns, but we’ll do our first one this way to help us stay organized as we go along. Class Limits Class Boundaries Tally Frequency Class Midpoint Relative Frequency Before we define the class limits, we must determine the class width. This is the size of the interval we will use. The class limits indicate the lowest and highest value that can fit into the class. There is a space between the upper limit of one class and the lower limit of the next class. The ½ way point is called the class boundaries. Tally marks are made each time a data value lands within the class limits. The frequency is the total number of tallies or the total number of data values within the class limits. The midpoint is the average of the lower and upper class limit. Lower + upper 2 This column represents the frequency of each class compared to the total of all frequencies. It is found by dividing the class frequency by the total number of data values. ( f/n ) We’ll use the class limits and the frequency or relative frequency to create a histogram to display our data after creating the frequency table to organize the data. Let’s use the data from Table 2-1 on page 37 to create a frequency table and a histogram.
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This note was uploaded on 11/29/2010 for the course BUS 101 taught by Professor Me during the Spring '10 term at Central Methodist University.

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Assign # 4 - Organizing Data (Frequency Tables and...

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