Path: janda.org/c10 > Overview of SPSS > Analyze > ONEWAY
Statistical Package for the Social Sciences

Syntax for Analysis of Variance Procedures

ANALYSIS OF VARIANCE
Several SPSS procedures test for statistically significant differences in means for an interval-level dependent variable when analyzed by two or more groups classified on a nominal scale. All of these procedures conduct an analysis of variance and produce an F-ratio as the test statistic.

Like z-scores and t-scores, F-ratios are interpreted with reference to a table of critical values--such as the F table on pages 710-717 in Kirk. Note that the magnitude of the F ratio must be interpreted with reference to two degrees of freedom. One for the numerator in the ratio and another for the denominator.

ANOVA is the general procedure for analysis of variance in SPSS, but ANOVA involves ideas not covered in our course. Instead, we will feature two very similar procedures:

• ONEWAY is the basic procedure for analysis of variance for interval-level variables when analyzed by one independent nominal variable.
• MEANS was developed just to compare means for an interval-level variable when broken-down into categories of several levels of nominal variables. It also generates an analysis of variance and produces the useful eta2 statistic for explained variance. I prefere MEANS over ONEWAY, but you should know both.

The syntax for the ONEWAY and MEANS commands are given below:

ONEWAY

"varlist" names the dependent interval-level variables to be analyzed. More than one dependent variable can be analyzed on a given ONEWAY run. Suppose that you wanted to analyze the percent of land under cultivation (in the POLITY data the variable would be landcult) across nations in the major regions of the world.

"varname" names the single nominal-level variable used to classify the several groups being compared. For example, "Region" in the table below might be the variable for the groups.

(min,max) indicates the range of values that embrace the groups being compared. For the "Region" variable in the POLITY dataset, specify (1,6).

 ```REGION seven world regions (POLITY dataset) Valid Cum Value Label Value Frequency Percent Percent Percent ANGLO-AMERICAN 1 5 4.5 4.5 4.5 EUROPEAN 2 17 15.3 15.3 19.8 LATIN AMERICAN 3 23 20.7 20.7 40.5 ASIA 4 15 13.5 13.5 54.1 MIDDLE EAST 5 11 9.9 9.9 64.0 AFRICA 6 32 28.8 28.8 92.8 EASTERN EUROPE 7 8 7.2 7.2 100.0 ----- ------ ------ Total 111 100.0 100.0 ```

ONEWAY
varlist BY
varname
(min,max) .

ONEWAY output

oneway landcult by region (1,7).
 - - - - - O N E W A Y - - - - - Variable LANDCULT % OF LAND UNDER ACTUAL CULTIVATION By Variable REGION seven world regions Analysis of Variance Sum of Mean F F Source D.F. Squares Squares Ratio Prob. Between Groups 6 9047.7478 1507.958 8.3937 0 Within Groups 100 17965.2509 179.6525 Total 106 27012.9987

MEANS

"varlist" names the dependent interval-level variables to be analyzed. More than one dependent variable can be analyzed on a given MEANS run.

"varname" names the multiple nominal-level variables used to classify the several groups being compared. For example, "Region" in the table below might be the first nominal variable for the groups and "country" might be the second.

The same variables analyzed under ONEWAY are used in this analysis with MEANS:

2 means landcult by region /statistics=anova.

 - - Description of Subpopulations - - Summaries of LANDCULT : OF LAND UNDER ACTUAL CULTIVATION By levels of REGION seven world regions Value Label Mean Std Dev Cases For Entire Population 18.5103 15.9637 107 REGION 1.00 ANGLO-AMERICAN 12.4 11.7601 5 REGION 2.00 EUROPEAN 29 17.5879 16 REGION 3.00 LATIN AMERICAN 11.5217 10.3874 23 REGION 4.00 ASIA 24.8571 15.4016 14 REGION 5.00 MIDDLE EAST 17.7 15.5456 10 REGION 6.00 AFRICA 11.1065 10.9881 31 REGION 7.00 EASTERN EUROPE 40.0375 14.7235 8 Total Cases = 111 - - Analysis of Variance - - Dependent Variable LANDCULT : OF LAND UNDER ACTUAL CULTIVATION By levels of REGION seven world regions Value Label Mean Std Dev Sum of Sq Cases 1.00 ANGLO-AMERICAN 12.4 11.7601 553.2 5 2.00 EUROPEAN 29 17.5879 4640 16 3.00 LATIN AMERICAN 11.5217 10.3874 2373.7391 23 4.00 ASIA 24.8571 15.4016 3083.7143 14 5.00 MIDDLE EAST 17.7 15.5456 2174.98 10 6.00 AFRICA 11.1065 10.9881 3622.1387 31 7.00 EASTERN EUROPE 40.0375 14.7235 1517.4787 8 Within Groups Total 18.5103 13.4035 17965.2509 107 Sum of Mean Source Squares d.f. Square F Between Groups 9047.7478 6 1507.958 8.3937 Within Groups 17965.2509 100 179.6525 Eta = .5787 Eta Squared = .3349

MEANS
varlist BY
varname BY
varname ...
/STATISTICS
=ANOVA.

MEANS

output