16a. Accessing Data: Means in SPSS ®

16a. Accessing Data: Means in SSPS ® 1 Prerequisites Recommended modules to complete before viewing this module  1. Introduction to the NLTS2 Training Modules  2. NLTS2 Study Overview  3. NLTS2 Study Design and Sampling  NLTS2 Data Sources, either 4. Parent and Youth Surveys or 5. School Surveys, Student Assessments, and Transcripts  9. Weighting and Weighted Standard Errors

16a. Accessing Data: Means in SSPS ® 2 Prerequisites Recommended modules to complete before viewing this module (cont’d)  NLTS2 Documentation 10. Overview 11. Data Dictionaries 12. Quick References  Accessing Data 14a. Files in SPSS 15a. Frequencies in SPSS

16a. Accessing Data: Means in SSPS ® Overview  Purpose  Exploring existing data Means Comparative means  Weights  Closing  Important information 3

16a. Accessing Data: Means in SSPS ® NLTS2 restricted-use data NLTS2 data are restricted. Data used in these presentations are from a randomly selected subset of the restricted-use NLTS2 data. Results in these presentations cannot be replicated with the NLTS2 data licensed by NCES. 4

16a. Accessing Data: Means in SSPS ® Purpose Learn to  Run simple statistical procedures Means Comparative means  Watch for Missing values n’s Weighted vs. unweighted data 5

16a. Accessing Data: Means in SSPS ® Means How to run means Means are run on continuous variables such as  Number of months  Income  Age  Test scores. Syntax DESCRIPTIVES VARIABLES=ndaAP_w /STATISTICS=MEAN MIN MAX. 6 These results cannot be replicated with full dataset; all output in modules generated with a random subset of the full data.

16a. Accessing Data: Means in SSPS ® Means From menu  Analyze: Descriptive Statistics: Descriptives  Select options and uncheck “Std Deviation” in pop-up box. Important: Although they print by default, do not use standard deviations (or optional standard errors) from this procedure.  These data are from a stratified sample, so standard errors are not calculated correctly in this procedure.  Standard errors in this procedure assume a simple random sample, not a complex sample. More about this later. 7 These results cannot be replicated with full dataset; all output in modules generated with a random subset of the full data.

16a. Accessing Data: Means in SSPS ® Means 8 These results cannot be replicated with full dataset; all output in modules generated with a random subset of the full data.

16a. Accessing Data: Means in SSPS ® Comparative means As with frequencies, comparative means can be run in a single step. The by- (or independent) variable must be categorical. Reminder: Do not include the standard deviation in statistics. Syntax MEANS TABLES=ndaAP_w BY na_age4 /CELLS MEAN COUNT. 9 These results cannot be replicated with full dataset; all output in modules generated with a random subset of the full data.

16a. Accessing Data: Means in SSPS ® Comparative means From menu  Analyze: Compare Means: Means  Locate [means variable name] in the variable list and click the right-facing arrow to the left of the “Dependent List” box to select it. Means variable  Locate [comparative variable name] in the list and click the right-facing arrow next to the “Independent” box. By-variable  Click on “Options” and under “Cell Statistics” select “Standard Deviation.”  Click the left-facing arrow.  Click Continue.  Press “OK” to run or select “Paste” to run code from syntax editor. 10 These results cannot be replicated with full dataset; all output in modules generated with a random subset of the full data.

16a. Accessing Data: Means in SSPS ® Comparative means 11 These results cannot be replicated with full dataset; all output in modules generated with a random subset of the full data.

16a. Accessing Data: Means in SSPS ® Means and comparative means: Example Means and comparative means  Open the Wave 3 parent/youth interview file.  Run means on np3NbrProbs.  Run comparative means on np3NbrProbs by W3_AgeHdr2005 and by W3_DisHdr2005.  Important: If you use the “Paste” option, you will be able to use this code again. 12 These results cannot be replicated with full dataset; all output in modules generated with a random subset of the full data.

16a. Accessing Data: Means in SSPS ® Means and comparative means: Example 13 These results cannot be replicated with full dataset; all output in modules generated with a random subset of the full data.

16a. Accessing Data: Means in SSPS ® Means and comparative means: Example 14 These results cannot be replicated with full dataset; all output in modules generated with a random subset of the full data.

16a. Accessing Data: Means in SSPS ® Means and comparative means: Example 15 These results cannot be replicated with full dataset; all output in modules generated with a random subset of the full data.

16a. Accessing Data: Means in SSPS ® Weights How to weight data. Running procedures unweighted is useful for exploratory analysis and recommended for becoming familiar with the data.  It is important to review the unweighted n’s However, unweighted results must never be reported. The procedures we used to calculate frequencies, means, crosstabs, and comparative means can be run with weights.  The weighted means or percentages will be correct.  The weighted standard errors will not be correct using these procedures; do not report them. Weighting in SPSS is a toggle.  The weight option can be turned on and off.  The procedures themselves do not change. Weights are applied when the weight toggle is on. Weights are not applied when the weight toggle is off. 16 These results cannot be replicated with full dataset; all output in modules generated with a random subset of the full data.

16a. Accessing Data: Means in SSPS ® Weights Syntax: weight on WEIGHT BY wt_npr1. Syntax: weight off WEIGHT OFF. Menu: weight on  Select “Weight Cases” from “Data” menu.  Click the “Weight Cases By” radio button.  Locate [weight variable] in the list of variables.  Click the right-facing arrow to select the weight.  Press “OK” to run or select “Paste” to run code from syntax editor. Menu: weight off  Select “Weight Cases” from “Data” menu.  Click the “Do Not Weight Cases” radio button.  Press “OK” to run or select “Paste” to run code from syntax editor. 17 These results cannot be replicated with full dataset; all output in modules generated with a random subset of the full data.

16a. Accessing Data: Means in SSPS ® Weights: Example Weights: Run earlier examples with a weight.  Run means example weighted with np3Wt. W3 parent interview weight np3wt np3NbrProbs np3NbrProbs by W3_AgeHdr2005 and by W3_DisHdr2005  Turn weight off. 18 These results cannot be replicated with full dataset; all output in modules generated with a random subset of the full data.

16a. Accessing Data: Means in SSPS ® Weights: Example 19 These results cannot be replicated with full dataset; all output in modules generated with a random subset of the full data.

16a. Accessing Data: Means in SSPS ® Weights: Example 20 These results cannot be replicated with full dataset; all output in modules generated with a random subset of the full data.

16a. Accessing Data: Means in SSPS ® Weights: Example 21 These results cannot be replicated with full dataset; all output in modules generated with a random subset of the full data.

16a. Accessing Data: Means in SSPS ® Closing Topics discussed in this module  Exploring existing data Means Comparative means  Weights Next module  17a. Accessing Data: Manipulating Variables in SPSS 22

16a. Accessing Data: Means in SSPS ® Important information  NLTS2 website contains reports, data tables, and other project-related information  Information about obtaining the NLTS2 database and documentation can be found on the NCES website  General information about restricted data licenses can be found on the NCES website  address: 23