Reliability Analysis: Statistics
You can select various statistics that describe your scale, items and the interrater agreement to determine the reliability among the various raters. Statistics that are reported by default include the number of cases, the number of items, and reliability estimates as follows:
 Alpha models
 Coefficient alpha; for dichotomous data, this is equivalent to the KuderRichardson 20 (KR20) coefficient.
 Omega models
 Estimation of McDonald’s omega to evaluate reliability.
 Splithalf models
 Correlation between forms, Guttman splithalf reliability, SpearmanBrown reliability (equal and unequal length), and coefficient alpha for each half.
 Guttman models
 Reliability coefficients lambda 1 through lambda 6.
 Parallel and Strict parallel models
 Test for goodness of fit of model; estimates of error variance, common variance, and true variance; estimated common interitem correlation; estimated reliability; and unbiased estimate of reliability.
 Descriptives for
 Produces descriptive statistics for scales or items across cases.
 Item
 Produces descriptive statistics for items across cases.
 Scale
 Produces descriptive statistics for scales.
 Scale if item deleted
 Displays summary statistics comparing each item to the scale that is composed of the other items. Statistics include scale mean and variance if the item were to be deleted from the scale, correlation between the item and the scale that is composed of other items, and Cronbach's alpha if the item were to be deleted from the scale.
 Summaries
 Provides descriptive statistics of item distributions across all items in the scale.
 Means
 Summary statistics for item means. The smallest, largest, and average item means, the range and variance of item means, and the ratio of the largest to the smallest item means are displayed.
 Variances
 Summary statistics for item variances. The smallest, largest, and average item variances, the range and variance of item variances, and the ratio of the largest to the smallest item variances are displayed.
 Correlations
 Summary statistics for interitem correlations. The smallest, largest, and average interitem correlations, the range and variance of interitem correlations, and the ratio of the largest to the smallest interitem correlations are displayed.
 Covariances
 Summary statistics for interitem covariances. The smallest, largest, and average interitem covariances, the range and variance of interitem covariances, and the ratio of the largest to the smallest interitem covariances are displayed.
 InterItem
 Produces matrices of correlations or covariances between items.
 ANOVA Table
 Produces tests of equal means.
 F test
 Displays a repeated measures analysisofvariance table.
 Friedman chisquare
 Displays Friedman's chisquare and Kendall's coefficient of concordance. This option is appropriate for data that are in the form of ranks. The chisquare test replaces the usual F test in the ANOVA table.
 Cochran chisquare
 Displays Cochran's Q. This option is appropriate for data that are dichotomous. The Q statistic replaces the usual F statistic in the ANOVA table.
 Interrater Agreement: Fleiss' Kappa
 Assesses the interrater agreement to determine the reliability among the various raters. A
higher agreement provides more confidence in the ratings reflecting the true circumstance. The
generalized unweighted kappa statistic measures the agreement among any constant number of raters
while assuming:
 At least two item variables must be specified to run any reliability statistic.
 At least two ratings variables must be specified.
 The variables selected as items can also be selected as ratings.
 There is no connection between raters.
 The number of raters is a constant.
 Each subject is rated by the same group containing only a single rater.
 No weights can be assigned to the various disagreements.
 Display agreement on individual categories
 Specifies whether or not to output the agreement on individual categories. By default, the output suppresses the estimation on any individual categories. When enabled, multiple tables display in the output.
 Ignore string cases
 Controls whether or not the string variables are case sensitive. By default, string rating values are case sensitive.
 String category labels are displayed in uppercase
 Controls whether the category labels in the output tables are displayed in uppercase or lowercase. The setting is enabled by default, which displays the string category labels in uppercase.
 Asymptotic significance level (%)
 Specifies the significance level for the asymptotic confidence intervals. 95 is the default setting.
 Missing

 Exclude both usermissing and system missing values
 Controls the exclusion of usermissing and systemmissing values. By default, usermissing and systemmissing values are excluded.
 Usermissing values are treated as valid
 When enabled, treats usermissing and systemmissing values as valid data. The setting is disabled by default.
 Hotelling's Tsquare
 Produces a multivariate test of the null hypothesis that all items on the scale have the same mean.
 Tukey's test of additivity
 Produces a test of the assumption that there is no multiplicative interaction among the items.
 Intraclass correlation coefficient
 Produces measures of consistency or agreement of values within cases.
 Model
 Select the model for calculating the intraclass correlation coefficient. Available models are TwoWay Mixed, TwoWay Random, and OneWay Random. Select TwoWay Mixed when people effects are random and the item effects are fixed, select TwoWay Random when people effects and the item effects are random, or select OneWay Random when people effects are random.
 Type
 Select the type of index. Available types are Consistency and Absolute Agreement.
 Confidence interval (%)
 Specify the level for the confidence interval. The default is 95%.
 Test value
 Specify the hypothesized value of the coefficient for the hypothesis test. This value is the value to which the observed value is compared. The default value is 0.
Specifying Statistics settings
This feature requires the Statistics Base option.
 From the menus choose:
 In the Reliability Analysis dialog, click Statistics.