Assignment 6

We will be talking about the concepts of Standard Deviation and the 68-95-99.7 rule in class on Thursday.

I won't have time to go over the IQR Rule, so hopefully I can put a good explanation of it here.

The IQR Rule is a way we determine if we have outliers. As we know, the IQR is the inter-quartile range, or (Q3-Q1). Here is the rule:

If an observation is GREATER than (1.5 multiplied by IQR) plus Q3, then the observation is a high outlier. If an observation is LESS than Q1 minus (1.5 multiplied by IQR), then the observation is a low outlier. In mathematical form:

Observation < Q1 -1.5*(Q3-Q1), then the observation is a low outlier and
Observation > Q3 + 1.5*(Q3-Q1), then the observation is a high outlier.

Let's do an example to make sure it makes sense. Let's say that my five number summary is as follows: 2, 10, 15, 20, 50. I want to know if 50 or 2 is an outlier. Let's do the math.

(Q3-Q1) = (20-10)=10.
1.5* 10 = 15

To Check for the high outlier:
Q3+15=20+15=35. Since 50>35, 50 is an outlier.

To check for the low outlier:
Q1-15=10-15=-5. Because 2 is NOT < -5, then 2 is NOT an outlier.

Hopefully that helps with that concept.

Questions 9-13 should not be that difficult. These all deal with concepts we discussed last Thursday. Particularly the mean and median ones: Remember, the median cuts the data in HALF (not necessarily where the peak is). Then remember where the mean goes based on skewed data.

Hope that helps,
Hillary