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IBM® SPSS® Data Collection Survey Reporter displays a message if you define a column means test on an unsuitable table or if you change a table that has a column means test defined so that it is no longer suitable for the test. When this happens, you can either adjust the table so that it conforms to the restrictions described here, or you can remove the test from the table. However, sometimes Survey Reporter is unable to determine that a table or a section of a table is unsuitable for the test until it actually attempts to perform it. When this happens, Survey Reporter simply skips the test.
Hierarchical data. This test is unsuitable for running on lower level data when you are working with hierarchical data. See the topic Hierarchical Data for more information.
Grids. It is possible to run this test on grids, provided that the test is carried out on a grid table structured in the format:
rating[..].Column * rating
This test is unsuitable for running on grid tables in the format:
rating * rating[..].Column
Weighting. This test is unsuitable for running when weighting is applied to individual columns or rows.
Mean rows. Survey Reporter can perform this test only if there is a mean row on the side axis. The mean row must be formed from a mean element. This can be a built-in mean or a mean added to the variable using the Edit Variable window. The test does not test mean values created using the Mean cell contents option.
The test does not test mean values created using the Mean cell contents option.
Columns. For each mean row, the test compares pairs of columns that are formed from variable categories. Survey Reporter does not compare columns that are formed from non-category elements or columns in which the number of cases contributing to the mean is zero. The test cannot be performed on tables that contain more than 52 category columns if you request one significance level, or 26 category columns if you request two significance levels, and it needs a minimum of two category columns.
Built-in Column Means tests. If a column means test is included in the metadata for a variable, the test is performed only if the variable is added as a single variable. If it is nested or concatenated with other variables, the built-in test is ignored to prevent possible inconsistencies in the results, and you must explicitly specify a column means test for the whole axis.
Nested tables. If there is nesting on the top axis, the test is performed separately for each set of columns that are formed from the categories of the innermost child variables. This means that the innermost child variables must have at least two categories. Nesting on the side axis does not change the test--each mean row is always tested.
Concatenated tables. If there is concatenation on the top axis, the test is performed separately for each set of columns that are formed from the categories of a concatenated variable. Concatenation on the side axis does not change the test--each mean row is always tested.
Built-in bases. If any of the variables on the top axis has more than one base element, the test will be performed separately for the columns formed from the categories before and after each base.
Sample size. This test relies on a central limit theorem approximation to the normal distribution. This means that a large sample (generally at least 30 cases) is required if the data is not distributed normally. However, when the data is distributed normally, a large sample is not necessary. Survey Reporter checks for small sample sizes, and does not carry out the test on columns with a base below 30. You can change the minimum sample size if required, by entering a new value in the Minimum Base field in the Statistics tab of the Table Properties dialog box.
Multiple response variables. When there is a multiple response variable on the top axis, Survey Reporter performs the overlap adjustment.
Excluded Elements. The column means test is performed whether or not it is carried out on a table containing elements that are excluded from the base using IncludeInBase=False. The calculation includes rows and columns corresponding to the excluded elements.
Overlap formula. Each axis can be derived from either an axis expression or an MDM variable. When an axis is derived from an axis expression, TOM will honor the MaxResponses property. When the MaxResponses value is greater or equal to 2, TOM regards the axis as overlapped. Considering that the MaxResponses default value is 2, each axis is in an overlap state by default.
When an axis is derived from an MDM variable, TOM will honor the variable's EffectiveMaxValue property. When the EffectiveMaxValue value is greater or equal to 2, TOM regards the axis as overlapped. When there are any sub-axis that are overlapped for a table's side and top, TOM regards the side or top as overlapped.
When both the side and top are overlapped for a table, and UseGridOverlapFormula is true, the grid overlap formula is applied to the table. The normal overlap formula is applied when the table's top is overlapped, otherwise the standard formula is used.
Refer to the following topics for more information regarding overlap:
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• MDM.IField.EffectiveMaxValue