Part of Data Quality Maturity Index (DQMI) methodology
Suppression rules
To address the data disclosure risk inherent in the presentation of small numbers, suppression has been applied to the data used in the DQMI. The first stage of suppression is that all individual data items with a total number of records less than 25 at the organisation level have been excluded from the data, except for when the corresponding coverage value is 0. Further suppression is then applied as detailed below;
APC, OP, ECDS and WLMDS
- Values between 1 and 7 replaced with an asterisk.
- The corresponding percentages for the percentage of Valid and Complete records are suppressed when the suppression takes place in the ‘Number of Records’ or ‘Valid and Complete’ columns.
- The corresponding percentages for the percentage of Valid and Complete records are recalculated to treat all ‘Excess in Defaults’ as valid (or 0) when the suppression takes place in ‘Defaults’ or ‘Defaults in Excess’ column.
- When only the ‘Defaults in Excess’ column is suppressed then ‘Defaults’ are replaced with an asterisk.
- All remaining integer values are rounded to the nearest 5.
DID
- Values between 1 and 2 replaced with an asterisk.
- The corresponding percentages for the percentage of Valid and Complete records are suppressed when the suppression takes place in the ‘Number of Records’ or ‘Valid and Complete’ columns.
- The corresponding percentages for the percentage of Valid and Complete records are recalculated to treat all ‘Excess in Defaults’ as valid (or 0) when the suppression takes place in ‘Defaults’ or ‘Defaults in Excess’ column.
- ‘Percentage of valid and complete’ is presented to the nearest whole number.
- When only the ‘Defaults in Excess’ column is suppressed then ‘Defaults’ are replaced with an asterisk.
- All remaining integer values are rounded to the nearest 5.
CSDS, MHSDS, IAPT and MSDS
- Values between 0 and 4 replaced with an asterisk.
- The corresponding percentages for the percentage of Valid and Complete records are suppressed when the suppression takes place in the ‘Number of Records’ or ‘Valid and Complete’ columns.
- The corresponding percentages for the percentage of Valid and Complete records are recalculated to treat all ‘Excess in Defaults’ as valid (or 0) when the suppression takes place in ‘Defaults’ or ‘Defaults in Excess’ column.
- ‘Percentage of valid and complete’ is presented to the nearest whole number.
- When only the ‘Defaults in Excess’ column is suppressed then ‘Defaults’ are replaced with an asterisk, with the exception for when ‘Defaults in Excess’ is equal to 0.
- All remaining integer values are rounded to the nearest 5.
Suppression rules differ to retain consistency with the standard Statistical reporting for these datasets, available in Appendix 3: Section Links to Information and Reports for Individual Datasets.
Names of datasets
APC - Admitted Patient Care
OP - Outpatient
ECDS - Emergency Care Data Set
DID - Diagnostic Imaging Data Set
CSDS - Community Services Data Set
MHSDS - Mental Health Services Data Set
IAPT - Improving Access to Psychological Therapies Data Set
MSDS - Maternity Services Data Set
WLMDS - Waiting List Minimum Data Set
Last edited: 17 August 2026 4:30 pm