Chapter 2Organizing Data

Frequency Distributions, Histograms, and Related Topics

Frequency Table – separates data into equal _________ or _____________ and shows how many data fall into each class.

Class limits – the __________ and ____________ values that can fit into a class.

Class Boundaries – class limits extended to the _______ ________________ between classes.

Midpoint – the _________________ of a class.

Relative frequency – the frequency of a class _________ ____ total of all frequencies.

Histogram – Similar to a bar graph in that the height of the bar represents the number of data / % in the class.

It differs from a bar graph in that the bars _________ and the width of the bar represents the _____________ ________________________.

Steps in Creating a Histogram1.Decide the number of classes (usually done for you).

2.Determine the class width = , then always _____________!

e.g. →

→

→

...8.116

71

...3.116

68

116

66

3. Set up _________________

4. Determine the _______________ in each class

5. Create the Histogram with the intervals on the __-axis and the frequency on the __-axis.

*Note Steps 2-4 create a Frequency Table.

Ex. An irate customer called Dollar Day Mail Order Company 40 times during the last two weeks to see why his order had not arrived. Each time he called, he recorded the length of time he was put “on hold” before being allowed to talk to a customer service representative.

Length of Time on Hold (min.)

1 5 5 6 7 4 8 7 6 55 6 7 6 6 5 8 9 9 107 8 11 2 4 6 5 12 13 63 7 8 8 9 9 10 9 8 9

Make a histogram using 5 classes.

Class width =

Class Limits Class Boundaries Midpoint Tallies Freq. Rel. Freq.

Distribution Shapes1.Symmetrical: a histogram in which both sides are (more or less) _______________________________________.

2.Uniform: a histogram in which every class has ________ ________________________________.

3.Skewed Left/Right: a histogram in which ____________ ______________________________. The direction of skewness is ______________________.

4.Bimodal: a histogram in which _____________________ _____________________________________________.

Descriptions of Histograms (Match each)

Symmetrical Uniform Skewed Left

Skewed Right Bimodal

Outlier(s): data value(s) that are ____________________ from other measurements in the data set. Usually extremely _____________.

Relative frequency histogram – same as a histogram except the bars measure _______________________ instead of _______________.

Cumulative Frequency: the sum of the frequencies for _________________________________________.

Ogive: a graph that displays ________________________.

Create an ogive for the given data.Grades Freq Cum freq

60-69 2

70-79 5

80-89 8

90-100 6

Assignmentp. 47 #7, 9, 10

see above question 7 for directions