Using the Analysis Definition Dialog

Analysis

This can contain:

• A list or range, consisting of comma separated variable names or TO ( ~)
• A survey expression, consisting of variable names separated by keywords WITH (:), AND(&), PER (%), NOT(!))
• Pre-defined tables such as Statistics table, Grid table, Holecount table

Break

Specifies the other axis used to split the data into subgroups.

This can contain:

• A list or range, consisting of comma separated variable names or TO ( ~)
• A survey expression, consisting of variable names separated by keywords WITH (:), AND (&), PER (%), NOT (!))

Pre-defined tables such as Statistics table, Grid table, Holecount table

Transpose

Switch the positions of Analysis and Break

Calculate

Specifies the type of analysis together with a field specifying the analysis data. There are six Calculate values.

• Counts & Percents (default option)
• Means & Significances
• Means & Differences
• Sum & Percents
• Means & Percents
• Means & %Differences

The variable entered in the Calculate box adjacent to the Calculate list box is used to calculate the means and sums.

Weight

• the name of a variable
• the name of a weight matrix and the variable to which it refers (e.g. WT1(Q10))
• a numeric value

Allow additional filters

Permits other filters to be applied to this analysis when used in reports. Clear this option if you always want this analysis to appear exactly as defined.

Show Options

The options available depend on the type of analysis selected in Content and Calculate.

All

Show all rows or columns in table or equivalent in chart

Top rows (or columns)

Display following number of rows (or columns) from start of table

Bottom rows (or columns)

Display following number of rows (or columns) to end of table

Rows (or columns) above

Display number of rows (or columns) above a specified value

Rows (or columns) below

Display number of rows (or columns) below a specified value

Retain ‘Other’ row (or column)

Creates ”Other’ category if rows (or columns) are limited

Order by

Defines the order in which the analysis data appears

• Default where items appear in the order they appear in the questionnaire
• Analysis Label sorts in alphabetical order by label
• Analysis Base sorts with the most popular reply first, based on the number of counts for each of the codes in the analysis variable.
• Score sorts on the statistics that have been added to the table, e.g. mean. If multiple statistics are selected, the one used will be the highest statistic in the list that can be sorted.

• Responses include all valid replies which may be greater than respondents in a multi-response survey.
• Respondents include all respondents

Update Display

Define when the analysis view is updated

• On request: update when is pressed
• On text change only: update if variable labels change
• On any change: update whenever respondent data changes

• Show to include the responses in analysis or/and break and display information on them. Enter text for label in field
• Hide to include the responses in analysis or/and break but do not show the information.
• Exclude to remove the responses from the analysis or/and break

Templates

Use Insert to insert one of

• base Current base value
• label The label of the analysis variable (grid or code)
• name The number or ID of the question used for analysis (headings only)
• score The weights placed on the different responses to a multi-choice question (labels only)
• unweighted unweighted base values (only useful if the base is weighted).
• You may also include free text, either on its own or to separate inserted fields.

Analysis Heading

Title for analysis group of rows. Defaults to the variable label (analysis question grid label).

Analysis Label

Title for analysis rows. Defaults to the analysis question code label.

Break Heading

Title for break group of columns. Defaults to the variable label (break question grid label)

Break Label

Title for break columns. Defaults to the break question code label.

Expand axis labels

If multiple variables are used, provide separate labels for each of the variables that appear on one axis. (Charts only). You can define the content of these labels in the Analysis and Break Heading and Label template fields.

Area

Description

Reports Include

Description

Include the detailed description defined in the Results Report dialog when you print an analysis from an analysis window

Notes

Include the notes entered in the Notes tab

Analysis text

Include the question text of the Analysis expression

Title

Include the title text entered in the Notes tab

Area

Description

Decimal places

Specify the number of decimal places shown on the following values

Counts

Defaults to 0

Means

Defaults to 0

Percentages

Defaults to 0

Sums

Defaults to 0

Show % sign

Select or clear the check box to display percentage sign. Defaults to on

Accuracy

Significant figures

Maximm number of significant figures. Defaults to 13 (including decimal places). If calculations exceed this number, the word OVERFLOW is shown.

Calculations d.p

The number of decimal places used in the calculations. Defaults to 2.

Suppress zeroes on specified axis

Remove rows and/or columns (as specified) in a table or chart where all responses are 0. (If you still wish to use them in confidence calculations, you will need to clear the Ordered values box on the Summary statistics tab)

Body cells appear as when is

Check box to specify the conditions under which an entire row or column is suppressed and the character to be used to replace the values field

Any cell appears as
when is

Check box to specify the conditions under which any individual cell in the table is suppressed. The default setting is to replace all zero (or less) values with a hyphen (-)

Body t-test/Body z-test

Displays t-test for Means and Significances analysis selected on the Definition tab and z-test if z-test is checked on the Definition tab for Counts and Percents.

Upper Level

Upper significance level

Lower Level

Lower significance level

Labels

Select Grouped or Continuous to choose how multiple break variables will be labelled

Show

All: All columns where they apply
Upper: Only show the columns with the upper significance level

Lower: Only show the columns with the lower significance level
Left: Only show the left-most column showing the significance level

Right: Only show the right-most column containing the significance level

Select one-tailed test when looking for an increase or a decrease between results

Set to None for no auto coding

Set to Clusters to auto categorise the data using a k-means cluster analysis

Set to Values to sort the quantity responses into code bands with one code per unique value

Literal

Set to None for no auto coding

Set to Values to create a code for each unique response (so “I like apples” and “I love apples” would have different codes.)

Set to Words to create a code for each unique word in a response (so “I like apples” and “I love apples” would have four codes, one each for “I”, “like”, “love” and “apples”)

Date

Set to None for no auto coding

Set to Values to sort date responses into code bands with one code per unique value

Time

Set to None for no auto coding

Set to Values to sort time responses into code bands with one code per unique value

Words and Values

Case sensitive

Create separate codes if responses use different cases.

Stop default words

Do not code words that are included in the stop list

Stop default values

Do not code values that are included in the stop list

Modify case

Change the case of words or phrases to the selected style

Limit codes

Set the maximum number of codes to be used (maximum number of 2000)

Clusters

Specify how open-response quantities will be coded into clusters

Clusters

Set the number of clusters to create

Iterations

Set how often the algorithm is repeated (higher numbers give greater accuracy but are slower)

Running means

Check to calculate the cluster centres every time a data case is allocated to a new cluster, rather than waiting until all cases have been evaluated.

Initial Centres

Specify the starting point of the calculations

Set to Zero (default) to start at 0 (in the n-dimensional space). Since the data has been standardised, this should be the centre point of all the variable data

Set to First case to use the data in the first respondent case as the starting point

Set to Evenly spread to spread the start points evenly across the n-dimensional space

Area

Description

Available

List of statistical data you can add to your chart/table

Used

List of statistical data you have added to your chart/table

Statistical data

<Body>

The analysis/break information given in definition

Confidence (mean)

Specify the confidence level and display the confidence interval level for the mean (using the defined scoring system)

Confidence Bottom Box

Specify a low-end group of values to be calculated and displayed. If confidence interval selected as an option, display the level of confidence that sample matches target population.

Confidence Difference

Display (top box percentage total) – (bottom box percentage total)

Confidence Top Box

Specify a high-end group of values to be calculated and displayed. If confidence interval selected as an option, display the level of confidence that sample matches target population.

Mean

Average value of the analysis variable(total divided by base) using the defined scoring system

Median

Central value (equal number of cases to each side

Significance (t-test)

Compare mean scores of columns with mean scores of the base to distinguish whether or not the difference between the groups’ averages would most likely reflect a “real” difference in the population from which the groups were sampled. The significance is shown as a percentage.

Standard Deviation

Display standard deviation (measure of dispersal of values and hence deviation from mean)

Standard Error

Display standard error (indication of how far individual scores deviate from the mean score)

t-test

Compare mean scores of axis-defined groups to see if difference is significant. Display significance letters by column values

U test

Compare median scores of axis-defined groups to see if difference is significant. Display significance letters by column values

Variance

Display variance (measure of dispersion of values in a distribution)

Statistic

Option

Meaning

Mean

Standard Error

Standard Deviation

Variance

Median

Score

Name of weight matrix, calculation, or name of variable to apply

Decimal places

Number of decimal places used in calculation

Confidence (mean)

Confidence Level

The level of certainty that the answer lies within the range given

Confidence Top Box

Confidence Bottom Box

Use the x y responses out of z to calculate q

Select the range of responses used to calculate the confidence top or bottom box. These will be the high-end responses for the top box and the low-end responses for the bottom box

Ordered values

Check to only use displayed (ordered) values in calculation and omit any suppressed zero values

at a confidence level of

(gap between sample and population) at the specified confidence level

Show confidence intervals

Check to display the confidence interval results

z-test

Check to display the z-test results with the confidence intervals

Multiplier

Allows you to modify the confidence interval if the sample is weighted or drawn from a small (or finite ) population. Set to sqrt(1-n/N) where n = sample size and N = population

Significance (t-test)

Comparison

Base used when comparing the mean of base to the mean of each category on your table. Either use:

Base: the mean for all respondents

Base less current: the mean for respondents that are not included in the category being compared.

Score

Name of weight matrix, calculation, or name of variable to apply (same as that used for Mean, Standard Error, Standard Deviation, Variance, Median)

Decimal places

Number of decimal places used in calculation

t-test

U test

Upper Level

Set the upper significance level

Lower Level

Set the lower significance level

Labels: Grouped
Labels: Continuous

Specify how the figures are shown for tables with more than one break variable

Show:

All
Higher
Lower
Left
Right

Select whether result is shown in both columns it affects, or whether it is only shown in one column. The column it is shown in may be:

column with the higher/lower value

column in the left-most/right-most position

Show:

Hyphen
Index

Check to show hyphens for non-significant results

Check to label columns with the letter used as index

1-Tail
2-Tail

Select type of test (crudely, 1-tailed when looking for increase/decrease between results;2-tailed when looking for difference between two mean scores)

Apply Tukey’s Correction (t-test only)

Apply Tukey’s Honestly Significant Difference (HSD) correction to take account of carrying out multiple t-tests

Results exclude the x y codes (U test only)

Enables you to exclude codes (eg, Don’t Know ) from the calculation

Statistic

Description

Count

The number of data cases

Mean

This is often called the average. It is defined as the sum of the items divided by the number of items. For example, for ten responses

Mean = (1 + 2 + 3 + 4 + 3 + 4 + 5 + 4 + 6 + 2) = 34 10 = 3.4

Mode

The mode of a distribution is the most frequent or most popular item. If two values tie for the mode, Snap chooses the lower. With the same ten responses: 1, 2, 2, 3, 3, 4, 4, 4, 5, 6

Mode = 4, since 4 is the most frequently occurring value (three occurrences).

Quartile 1

25% through a range of values

Median

The midpoint or 50% through a range of values. To calculate the median, the items of the distribution are arranged in order of magnitude starting with either the smallest or the largest, then:

if the number of items is odd, the median is the value of the middle item.

if the number of items is even, the median is the mean of the two middle items.

1, 2, 2, 3, 3, 4, 4, 4, 5, 6

Median = (3 + 4) ÷ 2 = 3.5

Quartile 3

75% through a range of values.

Sum

The sum is calculated by adding all the values of a distribution.

Sum = 1 + 2 + 3 + 4 + 3 + 4 + 5 + 4 + 6 + 2 = 34

Minimum

The minimum is the smallest value of the distribution.

Minimum = 1

Maximum

The maximum is the largest value of the distribution.

Maximum = 6

Range

The range shows the spread of the distribution and is calculated by subtracting the smallest value (minimum) from the largest value (maximum).

Range = 6 – 1 = 5

Standard Deviation

The standard deviation is a measure of dispersion of values in a distribution. It gives an indication of how much the values deviate from the mean. Thus, a distribution with a large range would have a larger standard deviation than one with a small range. The standard deviation is calculated as:

where x_i is each value in the distribution, is the mean of the values and n is the number of cases. For the sample in question:

Standard Deviation = 1.428286

Variance

The variance is another measure of dispersion of values in a distribution and is used in the calculation of the standard deviation:

Snap calculates the standard deviation and variance by assuming the data represents a sample rather than an entire population.

Standard Error of the Mean

The standard error of the mean is calculated by dividing the standard deviation by the square root of the number of items in the sample. It is defined as the standard deviation of the distribution of the sample mean and gives an indication of how far individual scores deviate from the mean score shown. The larger the sample, and/or the closer the individual scores are to the mean score, the smaller the standard error.

Standard Error of the Mean = 1.428286 ÷ √10 = 0.451664

Skewness

A distribution that is not symmetrical but has more cases toward one end of the distribution than the other is called skewed.

The measures of central tendency (mean, mode and median) can vary considerably. If the mean is larger than the mid point of the range (the median) and the most frequently occurring value (the mode), the sample is said to be positively skewed.

If the mean is smaller than the mid point of the range (the median) and the most frequently occurring value (the mode), the sample is said to be negatively skewed.

A small skewness value (close to 0) indicates that the data is evenly distributed about the mean. With this type of distribution it would be expected that the values for mean, mode and median be similar. The skewness of the example is 0.098843 indicating a small positive skewness.

Kurtosis

Kurtosis also gives an indication of the shape of a distribution in the form of the extent to which, for a given standard deviation, the data clusters around a central point.

A positive value for kurtosis indicates a distribution that is more peaked than usual. A distribution of this type would typically have most of the values clustered around a central point.

A negative value for kurtosis indicates a flatter or more widely dispersed distribution. The kurtosis for the example is -0.75202

Average Absolute Deviation

The average of the absolute deviations. It is a and tends to ignore distant outliers. It is a summary statistic of statistical dispersion and would normally only be displayed if specifically requested

Sample Standard Deviation

An estimate of the population standard deviation based on the sample.

Sample Variance

An estimate of the population variance based on the sample.