240 likes | 350 Views
Remember the 3 Ms? Mean, Median, and Mode ~Central Tendency~. Objective. The student will be able to calculate measures of central tendency (mean, median, and mode). = Average. Mean. The mean is the average of a data set To find the mean: Find the sum of the data items
E N D
Objective The student will be able to calculate measures of central tendency (mean, median, and mode)
= Average Mean • The mean is the average of a data set • To find the mean: • Find the sum of the data items • Divide by the number of data items. • The mean will Always be greater than the smallest number and less than the largest number. • These are data items: 2, 3, 4, 5, 8, 8, and 12 2 + 3 + 4 + 5 + 8 + 8 + 12 7 (total data items) 42 / 7 = the mean, which is 6
Mean is the average of a set of data. To calculate the mean, find the sum of the data and then divide by the number of data.
Central Tendency • The Central Tendency is the center of the distribution of a data set. • The mean of a set of data is the most common measure of Central Tendency. • Other measures are mode and median
A way to remember…Mean – It is very mean because it makes you do all that work! grrrrrrrrr You try the next one!
ABC Warehouse sells flat screen TVs at the following prices: $350, $275, $500, $325, $100, $375, and $300. What is the mean price?
Outliers • Values that are much higher or lower than others in a data set are Outliers. • High temperatures Monday through Friday were 80, 81, 60, 77, and 82. Identify the outlier in the data.
MedianWhat does this word make you think of… • The middle number of a set of data, arranged in numerical order • Median is the middle of the road
How Tall are You? • Need 5 volunteers: • What is the median height? • Need 1 more volunteer • What is the median height? • What was different about our middle number? • Odd Number of Data Items: • the middle number when the data items are put in numerical order. • Even Number of Data Items: • the two middle numbers when data items are put in numerical order.
Median • Find the median of this data set • 4, 3, 7, 9, 5, 3, 1 • Put them in order! • There are 7 numbers in total…looking for the “middle” number • Median =
ModeWhat does this word make you think of? • Mode: the data item that occurs the MOST • What is the mode from our previous data set? • 4, 3, 7, 9, 5, 3, 1 • 3 is a mode for these data items.
How old are you? • Raise your hand if you are: • 13 • 14 • 15 • 16 • What is the mode?
Mean The average Median The number or average of the numbers in the middle Mode The number that occurs most
Find me the M, M & Ms • 12, 14, 26, 37, 8, and 14 • Re-order: 8, 12, 14, 14, 26, 37, 26. • Mean: 19.6 • Median: 14 • How many Modes: 2 • Mode: 14, 26
Find me ONLY Mode: • Grape, grape, banana, nectarine, strawberry, strawberry, strawberry, orange, watermelon. • How many modes? • Just one: strawberry.
Find me the M, M & Ms • 2.3, 4.3, 3.2, 2.9, 2.7, and 2.3. • Re-order: 2.3, 2.3, 2.7, 2.9, 3.2, 4.3. • Mean: 2.95 • Median: 2.8 • How many Modes? 1 • Mode: 2.3
Outlier • Outlier: is a data item (data value) that is much higher or lower than the other data values. • Outliers can affect the mean of a group of data. • Example: 2, 3.5, 1, 2, 5,000,000. • Example: 35, 45, 40, 37, -6.
Describing Data with M, M, & M. • You can use what you know about Mean, Median, and Mode to describe data. • But figuring out which M describes it best is difficult. I think mode describes it best! Nah! Its got to be mean!
Which M, M, & M is best? • The favorite movie of students in the eighth grade class? • Mode: good for non-numerical data items and for frequent occurrences.
Which M, M, & M is best? • The distances students in your class travel to school. • Median: one student may live much further than everyone else. When an outlier may significantly influence the mean, we use median.
Which M, M, & M is best? • The daily high temperature during a week in July. • Mean: since daily temp. are not likely to have outlier, mean is best. When data have no outlier, use mean.
Measures and Central Tendency • Your text book is going to ask you determine which MEASURE of CENTRAL TENDENCY best describe the data. • Its just asking you to figure out which M works with the data best!