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Spell out your full name (first, middle and last) Be ready to share the following counts: Number of letters in your full name. Number of vowels Number of consonants
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Section 2-1 Organizing Data
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After completing chapter 2, you should be able to Organize data using frequency distribution Represent data in frequency distributions graphically using histograms, frequency polygons, and ogive Represent data using Pareto charts, time series graphs, and pie graphs. Draw and interpret a stem and leaf plot.
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Objective 1: Organize data using frequency distributions. Each raw data value is placed into a quantitative or qualitative category called a class. The frequency of a class is the number of data values in a specific class. When data are collected in the original form, they are called raw data.
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Frequency Distributions A frequency distribution is the organization of raw data in table form, using classes and frequencies.
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A categorical frequency distribution is used for data that can be places in specific categories, such as nominal or ordinal level data. Categorical Frequency Distribution
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Example 2-1 Twenty-five army inductees were given blood test to determine their blood type. The data set is: Construct a frequency Distribution ABBABO OOB B BBOAO AOOO AOBA
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Make a Table Blood Type Tally Frequency f Relative frequency; % A B AB O n= total number of values
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Grouped Frequency Distributions When a range of data is large, the data must be grouped into classes that are more than one unit in width, in what is called a Grouped Frequency Distribution.
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Number of hours boat batteries last: Class limitsClass boundaries FrequencyCumulative frequency 24-303 31-371 38-445 45-519 52-586 59-651
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Vocabulary Lower Class Limit Upper Class Limit Lower and upper class limits should have the same number of decimal points as the raw data. Range: R= maximum value – minimum value
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Class boundaries Class boundaries are used to separate the classes so that there is no gap in frequency distribution. Class boundaries should have one more decimal place value than the raw data. Class boundaries always end in a 5 How to find the boundaries: Lower limit – 0.5= lower boundary Upper limit + 0.5=upper boundary
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More terms to know Class Width is difference between lower and upper class limits. Class Midpoint X m
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Make a Table ClassTally Frequency f Relative frequency; % n= total number of values
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Example 2-2 These data represent the record high temperatures (F) for each of the 50 states. Construct a grouped frequency distribution for the data using 7 classes. 112100127120134118105110109112 110118117116118122114 105109 107112114115118117118112106110 116108110121113120119111104111 120113120117105110118112114
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Solution to 2-2 Step 1: determine the classes by following the steps outlined below : Find the Range. The range, R=maximum value- minimum value Select the number of classes desired; usually between 5 and 20
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Find the class width: Round UP to the nearest whole number Start with lower class limit, usually the lowest value, keep adding the width until you have the desired number of classes.
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The values you have obtained are the lower class limits. Determine the upper class limits for each class but subtracting one from the lower class limit of the next class. Determine the each class boundary. Step 2: Now start the tallying process.
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To construct a frequency distribution follow these rules. (pg 38) 1) There should be 5-20 classes. 2) The class width should be an odd number. 3) Mutually exclusive 4) Continuous 5) Exhaustive 6) Equal in width
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Ungrouped Frequency Distribution When the range of the data values is relatively small, a frequency distribution can be constructed using single data values for each classes. This type of distribution is called an ungrouped frequency distribution.
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Example 2-3 A data shown here represent the number of miles per gallon that 30 selected four-wheel-drive sports utility vehicles obtained in city driving. Construct a frequency distribution and analyze it. 121712141618 161812161715 16121516 1214151215 191316181614
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Page 44 Procedure Table And then on the next page: 5 reasons for constructing frequency distribution
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Homework Applying Concepts page 45 make sure to answer all questions. Exercises 2.1 page 46 #5, 7 and 13. Use graph paper and ruler.
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