stat 119

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Name:___________________

Math 160 Lab 1 – Introduction to StatCrunch Ch 1 – 3 – Due on the day of your midterm exam.

Explanation of the data that you will be looking at:

Bears are anesthetized for a variety of reasons. In areas that humans and bears cohabit, bears may be anesthetized by wildlife managers for translocation and/or marking. Bears may be anesthetized for research purposes or for medical management of sick bears.

Here are the 9 variables in our data set:

Age = is the age of the bear in months

Month = the month the bear was measured (Jan – Dec)

Sex: female = 1 and male = 2

Headlen = head length in inches

Headwth = head width in inches

Neck = distance around neck in inches

Length = length of body in inches (not including head)

Chest = Distance around chest (in inches)

Weight = weight of bear measured in pounds

Question 1: Looking at the variables ( not the actual data values ), answer the following;

a) Which variable(s) are qualitative?

b) Which variable(s) are quantitative?

c) Looking at your quantitative variable(s) do you have any that are discrete?

d) Which variable(s) are nominal?

e) Which variable(s) are ordinal?

f) Which variable(s) are interval?

g) Which variable(s) are ratio?

Question 2: Put Frequency table results for LENGTH here. Label each table according to gender ( don’t leave it as 1 or 2, you need to label as male bears of female bears)

a) Do you have a concern with the class limits? If so, go back to the raw data to see how you should edit your table. Copy the tables from above and edit them as needed.

b) Using this relative frequency table find the mean LENGTH for male and the mean length for female bears.. Notice that this mean is different than if you found the mean using the raw data. Show your work.

c) What percentage of male bears had a body length between 60 to 70 inches?

Question 3: Put your Histogram for AGE here

a) How many bears are in our sample?

b) What percentage of bears where younger than 50 months?

c) Find the Mean given the information on this histogram. The Mean obtained from this Histogram will be slightly different than the mean obtained from the raw data. You must calculate the Mean from the information on this histogram. Show your work.

d) Estimate the median age using the histogram

e) Estimate the mode age using the histogram.

f) Identify the type of distribution by using the information you have gathered so far.

Question 4: Paste your summary statistics tables here.

a) Re-type the mean and standard deviation below round accordingly to the rules we talked about in class.

Mean Female Bears = Standard deviation (Female Bears) =

Mean Male Bears = Standard deviation (Male Bears) =

b) What percentage of female bears have a length above 70.5 inches?

c) Find the IQR for female bears and the IQR for male bears.

d) Which has the most variable length?

e) If you wanted to calculate the EXACT mean and the data was presented to you in three ways. Which would you use to find the EXACT mean ( we don’t want an estimate of the mean – we want the real mean)

i) Raw Data

ii) Grouped Data (frequency table)

iii) Histogram

Question 5: Paste you boxplot here

a) Compute the IQR for both males and females.

b) Which group had the most variable weight?

c) Find the median weight for male and female bears.

d) What percentage of male bears weighed above 200 lbs?