Learning Guide
National Crime Victimization
Survey
SPSS Drop-Down Menu
Overview
This example will show how to calculate victimization rates for violent crime. You can follow similar steps to find the rate of property crime.
The difficulties in calculating rates are knowing which numbers to use, which files to take them from, and what adjustments need to be made. The basic tasks are:
- Use the incidents data to find the number of violent victimizations, which will be the numerator.
- Use the persons data to find the number of persons age 12 and older at risk, which will be the denominator.
- Calculate the rate of violent crime, dividing the count of violent victimizations by the number of persons at risk and multiplying by 1,000.
Optional: Creating Syntax While Using Menus
The drop-down menus in SPSS offer convenient data-analytic options. Menus are useful for learning about unfamiliar commands. While this section does not require typed syntax, it is helpful to know you can create and save syntax while using the menu option. Once you have finalized the details of commands, you will see a Paste button next to the OK button. If you click Paste instead of OK, SPSS will open up a syntax window containing the relevant command in a syntax format. You may execute this command from the window, and you may save the contents as a syntax file for future analysis. If you highlight the created syntax statement, and then pull down the Run menu, selecting the Selection option will execute the commands. The result is the same as if you had clicked the OK button before. Note: you do not need to learn how to create syntax files to complete the exercise below.
Steps
Step 1: Access the incident-level data file.
You will first use incidents2015.sav to calculate the number of violent victimizations.
Pull down the File menu and select the Open option, then the Data option. Navigate to the folder ICPSR_36448\DS0004, select incidents2015.sav, and click the Open button.
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Step 2: Exclude crimes occurring outside the United States.
The victimization rates published by the Bureau of Justice Statistics only include incidents taking place inside the United States. Because some respondents report incidents that occurred in other countries, you will need to take this into account.
You will use V4022 to restrict the data to crimes that did not occur outside the U.S.
Pull down the Data menu and select the Select Cases... option. Under the Select section, select the If condition is satisfied option and click the If... button that becomes available.
In the argument box that becomes available, type "V4022 ~= 1".
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Click the Continue button, and back at the Select Cases window click the OK button to execute the select command.
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Step 3: Create a variable that captures the total number of violent victimizations.
Codes to identify the specific types of crime are contained in V4529. NCVS codes for violent crimes range from 1 to 20.
Using value ranges of V4529, you will create a new variable VIOLENT indicating violent crimes.
Pull down the Transform menu and select Recode into Different Variables...
To view variable lists using names rather than descriptives labels, right-click anywhere on the variable list and select Display Variable Names. You will need to do this every time you choose a variable by name from a variable list.
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Locate V4529 in the variable list and click the arrow to move it into the Input Variable -> Output Variable box on the right.
Under the Output Variable section Type "VIOLENT" in the first box. Click the Change button to add "VIOLENT" to the Input Variable -> Output Variable box.
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Click the Old and New Values... button.
First, under the Old Value section, select Range. Type "1" in the first box that becomes available and "20" in the second. In the New Value section type "1." Then click the Add button to create this rule in the Old --> New section.
Second, under the Old Value section, select All other values. In the New Value section type "0." Click the Add button to create this rule in the Old --> New section.
Finally, click the Continue button, and back at the Recode into Different Variables window click the OK button to execute the recode command.
In this step, you have created a variable named VIOLENT with all violent crimes coded as 1 and all other crimes coded as 0.
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Step 4: Find the weighted number of victimizations.
You will apply the victimization weight SERIES_WEIGHT to the data. Then you will run a frequency report on your violent crime variable VIOLENT to receive estimates for the U.S. population.
Pull down the Data menu and select the Weight Cases... option.
Select the Weight cases by option. Locate SERIES_WEIGHT at the bottom of the variable list and click the arrow to move it into the Frequency Variable: box on the right.
Click the OK button to execute the weight command.
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Pull down the Analyze menu and select the Descriptive Statistics option, then the Frequencies... option.
Locate VIOLENT near the bottom of the variable list and click the arrow to move it into the Variable(s): box on the right.
Click the OK button to execute the frequencies command.
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In the Output window, you should see in the result of the frequencies command that 5,006,615 cases in the weighted data have VIOLENT = 1.00. Record this number outside SPSS, as it will be your numerator for the final rate calculation.*
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Step 5: Access the person-level data file.
Finding the denominator for the rate of violent victimization will be easier. You will use use persons2015.sav to calculate the number of persons aged 12 and older.
Pull down the File menu and select the Open option, then the Data option. Navigate to the folder ICPSR_36448\DS0003, select persons2015.sav, and click the Open button.
Whenever you open new data file with a modified data file open, SPSS will pop up a window asking "Save changes to the following dataset?" If you have followed these instructions and wish to save the variables you have created, you can safely click the Yes button because you did not overwrite or delete any existing variables or cases.
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Step 6: Find the weighted number of persons.
Unlike the incidents data, the persons data require no additional corrections from you. You will simply weight the data using the included variable WGTPERCY, then run a frequency report to find the total number of persons age 12 or older at risk of violent victimization in the population.
Pull down the Data menu and select the Weight Cases... option.
Select the Weight cases by option. Locate WGTPERCY in the variable list and click the arrow to move it into the Frequency Variable: box on the right. Remember that you will need to right-click on the variable list and select Display Variable Names every time you choose a variable by name from a variable list.
Click the OK button to execute the weight command.
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Pull down the Analyze menu and select the Descriptive Statistics option, then the Frequencies... option.
Locate V3001 at the top of the variable list and click the arrow to move it into the Variable(s): box on the right.
Click the OK button to execute the frequencies command.
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In the Output window, you should see in the result of the frequencies command that the weighted persons data produces a total of 269,526,471 cases. Record this number outside SPSS, as it will be your denominator for the final rate calculation.*
You will see SPSS add a message about Warning #3211 after the output from the frequencies command. This is expected, due to the weight calculations used in this particular data, and it does not affect your results.
Step 7: Calculate the violent and property victimization rates.
You'll have to do this part by hand. Use a calculator to compute the rates. The rate of violent victimization per 1,000 persons is:
Congratulations! You have replicated the official statistics published in Criminal Victimization, 2015.
*Note: Because BJS rounds to the nearest 10, the numbers you will find in this exercise are slightly different from the numbers in the Criminal Victimization, 2015 report.