# Consistency

The absence of difference, when comparing two or more representations of an object against a definition.

{% hint style="info" %}
Do not confuse consistency with accuracy or correctness.
{% endhint %}

Consistency can refer to ensuring that data values are consistently represented within a dataset and between datasets, and consistently associated across datasets Or the degree to which data values of two sets of attributes within a record comply with a rule. Or the degree to which the data values of a set of attributes of a dataset at different points in time comply with a rule.

In consistency two or more data values are compared.

There are various types of consistency: 

Consistency within a record: The degree to which data values of two sets of attributes within a record comply with a rule 

Consistency between records within a dataset: The degree to which data values of two sets of attributes between records comply with a rule 

Consistency across datasets: The degree to which data values of two sets of attributes between datasets comply with a rule 

Consistency over time (temporal consistency ): The degree to which the data values of a set of attributes of a dataset at different points in time comply with a rule. 

Consistency across metadata: Is all the metadata consistent, or does it conflict with other metadata? For example, does a usage business rule demand that data be used when the creation business rules state it hasn’t been created yet? Plausibility of data values can be seen of a type of consistency. 

A rule can be an equation with a =, > or < symbol.  For example, profit = return – costs.&#x20;

A rule can also be a business rule. For example, one might expect that the number of transactions each day does not exceed 105% of the running average number of transactions for the previous 30 days.&#x20;

Reference Data item measured against itself or its counterpart in another dataset or database.

**Measure:** Analysis of pattern, semantic relatedness, and/or value frequency.

**Unit of Measure:** Percentage.

Example(s): School admin: a student’s date of birth has the same value and format in the school register as that stored within the Student database.


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