02-08-12

2.1) #15. Assume 6000, multiply percent by 6000 to find counts. Barchart for categorical data from Table.

41. Supermarkets - 73357/198514 = 36.94% (37%)
Delicatessens - 6123 / 198514 = 3.1%
SKIP 16! Pie charts are unimportant.

What is a histogram good for? Quantitative Data
How is a histogram different from a bar chart? Data is continuous.

Reviewed Sorting and Calc features of Minitab (02-06-2012)

Exercise: Make a histogram with fit of the "calories/gram" column you created and evaluate the distribution. Is it symmetric? Is it skewed? Where does the center lie? What is the spread? Are there any outliers?

Quiz #1 will cover homework sections assigned up to 2.2
~5 (involved) questions, similar to the "applying concepts" type questions in the textbook.
Everything on the quiz has been covered in class. There are no "trick" questions, take the questions at face value. If you have a question, be safe, ask.
You will need: A blue/green book, which you can purchase in the book store or cafeteria.
You are allowed: a 3x5" card with hand written notes for when you blank

Review questions:
1.  Suppose that the observational units in a study are patients arriving at an emergency room on a particular day.  For each of the following, indicate whether it is a legitimate variable or not.  If it is a variable, classify it as quantitative, binary categorical, or categorical (non-binary).  If it is not a variable, explain why not.
a) blood type
b) whether or not men have to wait longer than women
c) number of patients that arrive before noon
d) number of stitches required

2.  Suppose that you are given a sample of 25 Reese's Pieces candies and asked to record the color of each candy.
(a)  What are the observational units here?
(b) What is the variable here?  Is it categorical (binary?) or quantitative?
(c) Now suppose that each of your classmates is also given a sample of 25 Reese's pieces candies.  Also suppose that everyone is asked to report the percentage of yellow candies in her sample of 25 candies.  Now what are the observational units?  (Be careful -- the observational units are not the same here as they were in part (a).)
(d) Now what is the variable?  Is it categorical (binary?) or quantitative?

3. Researchers at Stanford University studied whether or not reducing children's television viewing might help to prevent obesity. Third and Fourth grade students at two public elementary schools in San Jose were the subjects. One of the schools incorporated a curriculum designed to reduce watching television and playing video games while the other school made no changes to its curriculum. At the beginning and each of the study a variety of variables were measured on each child. These included body mass index, tricep skinfold thickness, waist circumference, waist-to-hip ratio, weekly time spent watching television and weekly time spent playing video games.
a) Identify the type of study
b) Identify the observational units
c) Identify the variables (quantitative or categorical, if categorical are they binary?)