STATISTICS

A statistic is a number .

If we ask how many people in the classroom are over 6 feet in height the resulting number is a statistic . How many students are between 5’ and 6’ ? This number gives us a second statistic . We can collect these statistics and make some observations. The number of teens that have taken up cigarettesis another example of a statistic. A baseball players batting average is a statistic. A FREQUENCY DISTRIBUTION breaks statistical data down into classes. If Iook at all the different birthdays in this class room I could break them into classes as in the following Frequency Distribution Table :

Class_____________Frequency____________________

Jan - March......................9

Apr-June .........................7

July-Sept ....................... 12

Oct-Dec .........................10

The Frequency column represents the number of students with birthdays in the month given in the class column .

STATISTICAL MEASURES

From the reading : What are the statistical measures ?

What is the definition of each of these ?

RANGE : The difference between the highest and lowest statistics .

MEAN: The sum of the statistics divided by the number of statistics .

MEDIAN: After the numbers are ordered , the center number or the average of the two center numbers .

MODE . The statistic that occurs most frequently . More than one mode is possible !!
 
 

APPLICATIONS OF STATISTICAL MEASURES

Example

Suppose we have had 12 hw assignments and your scores are as follows :

7 , 6 , 5 , 10 , 10 , 0 , 9 , 8 , 7 , 10 , 9 , 0 .

To find the median of these scores you would need to put the data in ascending order first:

0 , 0 , 5 , 6 , 7 , 7 , 8 , 9 , 9, 10 , 10 , 10

Because there is an even number of statistics , we have two numbers in the middle . We add the two middle numbers and divide by 2 to get the median . In this case the two middle numbers are 7 and 8 so the median is 15 / 2 .

Will the mean , median or mode give you a higher average score ? What is the range of the grades ?