Data Assignment #2: Probability
Instructions: This assignment is meant as a review of levels of measurement and basic descriptive statistics, and includes some new questions on probability. The questions require the use of the data file Homicide 2005b.sav in PSPP or SPSS. Students will have to look at Variable View to see what information is available, then use frequency tables and crosstabs to display the data and answer the questions.
a. Properly format your document (name, date, title of assignment).
b. You may use this document as a template for your answers.
c. Include a copy of each relevant table from SPSS or PSPP.
PART 1 – Review of Level of Measurement
You should be able to identify what type of variable you are working with by exampling the format and distribution in a dataset. One way is to run a frequency table – but you but also look at the variable make-up (in SPSS – this is the Variable View). Do not rely on the “level of measurement” label in the variable view.
What is the level of measurement used for the values of the following variables?
a. PCT (Precinct)
b. HOMYEAR (Incident Year)
c. Race (Race of Vic)
d. Age (Age of Vic)
e. Agerec (Age in 4 groups)
Part 2 – Review of Descriptive Statistics
You should know how to run basic descriptive in SPSS/PSPP. You also need to know how to generate a frequency table. All of this can be run through the ANALYZE > DESCRIPTIVE STATISTICS tab in SPSS/PSPP.
For each variable, what is the category with the highest frequency or mode?
For each variable, what is the average value, or mean?
m. How many homicide victims are at least 35 years old?
The best way to generate this result is to export (or copy and paste) your frequency table on the age variable – to Excel and then add (sum) the frequency of rows for age 35 and older. Alternately – you can SORT the frequency table in a manner to give you the cumulative frequency you need.
Part 3 – Finding Probability: