Discussion Board Forum 1/Project 2Instructions

Standard Deviation and Outliers

Thread:

For this assignment, you will use the Project 2 ExcelSpreadsheet to answer the questions below. In each question, usethe spreadsheet to create the graphs as described and then answerthe question.

Put all of your answers into a thread posted in Discussion BoardForum 1/Project 2.

This course utilizes the Post-First feature in all DiscussionBoard Forums. This means you will only be able to read and interactwith your classmates’ threads after you have submitted your threadin response to the provided prompt. For additional information onPost-First, click here for a tutorial. This is intentional. Youmust use your own work for answers to Questions 1–5. If somethinghappens that leads you to want to make a second post for any ofyour answers to Questions 1–5, you must get permission from yourinstructor.

1. A. Create a set of 5 points that are very close together andrecord the standard deviation. Next, add a sixth point that is faraway from the original 5 and record the new standarddeviation.

What is the impact of the new point onthe standard deviation? Do not just give a numerical value for thechange. Explain in sentence form what happened to the standarddeviation.

B. Create a data set with 8 points init that has a mean of approximately 10 and a standard deviation ofapproximately 1. Use the second chart to create a second data setwith 8 points that has a mean of approximately 10 and a standarddeviation of approximately 4. What did you do differently to createthe data set with the larger standard deviation?

1. Go back to the spreadsheet and clear the data values fromQuestion 1 from the data column and then put values matching thefollowing data set into the data column for the firstgraph.

50, 50, 50, 50, 50.

Notice that the standard deviation is0. Explain why the standard deviation for this one is zero. Do notshow the calculation. Explain in words why the standard deviationis zero when all of the points are the same. If you don’t know why,try doing the calculation by hand to see what is happening. If thatdoes not make it clear, try doing a little research on standarddeviation and see what it is measuring and then look again at thedata set for this question.

1. Go back to the spreadsheet one last time and put each of thefollowing three data sets into one of the graphs. Record what thestandard deviation is for each data set and answer the questionsbelow.

Data set1:       0, 0, 0, 100, 100,100

Data set2:       0, 20, 40, 60, 80,100

Data set3:       0, 40, 45, 55, 60,100

Note that all three data sets have a median of 50. Notice howspread out the points are in each data set and compare this to thestandard deviations for the data sets. Describe the relationshipyou see between the amount of spread and the size of the standarddeviation and explain why this connection exists. Do not give yourcalculations in your answer—explain in sentence form.

For the last 2 questions, use the Project 1 Data Set.

1. Explain what an outlier is. Then, if there are any outliers inthe Project 1 Data Set, what are they? If there are no outliers,say no outliers.
2. Which 4 states have temperatures that look to be the mostquestionable or the most unrealistic to you? Explain why youselected these 4 states. For each state, give both the name and thetemperature.