Ch 6.3 - Standard Deviation and Z-score Activity: Do Action! activity on page 278/279 #1-5 variance: the average squared difference of the scores from the mean HW: page 275 #1, 3, 5, 9 39 51 35 22 28 67 57 42 56 74 51 87 99 48 36 28 57 23 53 74 22 23 28 28 29 35 36 42 48 51 51 53 56 57 57 67 74 74 87 99 6.3 February-24-15 3:00 PM MDM4U Page 1
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MDM4U - Mr Nyman - 6.3.pdf/542845742...MDM4U Page 1 . Problems with variance: • more 'weight' is given to extreme (very large or small) values • gives units squared, which is different
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Ch 6.3 - Standard Deviation and Z-score
Activity: Do Action! activity on page 278/279 #1-5
variance: the average squared difference of the scores from the mean
Problems with variance:more 'weight' is given to extreme (very large or small) values•gives units squared, which is different than the units of the data•
standard deviation: the square root of the variance; the average distance of the scores from the mean
Ex1 - Std Dev. in Graphs
Which graph has a greater standard deviation?
graph 1 graph 2
If the variation on graph 1 is 1.5, what is the std. dev.?
What would graph 1 look like if the standard deviation were 1.8?
MDM4U Page 2
What would graph 1 look like if the standard deviation were 1.8?
Ex 2 - Std Dev. from data
Find the mean and std. dev.1 2 3 4 2 1 2 4 2 3 3 3 4 1 1 2 3
What would to the std dev if the values were all 1 higher?
z-score: the number of std dev an observation is from the mean
Ex 3: z-score
A data set has a mean of 5 and a std dev of 1.2, determine the z-scores for data with values of 6.2 and 3.