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# Policy Adjustments and HIPAA Expert Determination (Public Preview)

Audience: Project Owners

Content Summary: This page outlines the Policy Adjustment, Expert Determination, and Keep Fields in the Clear features.

These Public Preview features must be enabled on the App Settings page.

Project owners can use Policy Adjustments to increase a data set's utility while retaining the amount of k-anonymization that upholds de-identification requirements. With this feature enabled, users can redistribute the noise across multiple columns of a data source within a project to make specific columns more useful for their analysis. Since these adjustments only occur within the project and do not change the individual Data Policies, data users must be acting under the project to see the adjustments in the data source.

Navigate to Adjust a Policy for a tutorial.

The data source below masks these columns with k-anonymization: Account Type, Education, EmploymentStatus, Gender, and Location Code. When the analyst examines the data, the percent NULL has been predetermined by Immuta with an equal weight across all of these columns. However, if the analyst's work hinges on the EmploymentStatus column, the project owner can adjust the weights on the Policy Adjustment tab in the project to make the necessary data (EmploymentStatus) less NULL.

Here the default weight has been equalized across the columns giving the same amount of importance to all of the data, allocating the noise to allow the most use possible across all of the masked columns.

Here the weight is manually adjusted to lower the percent NULL and make the needed column (EmploymentStatus) more usable while still retaining the necessary amount of de-identification by redistributing the noise across the other columns.

### Weight Distribution and Percent Null

For columns that are already well-disclosed (have a low Percent Null), the same Percent Null will display even when you drastically change the weight distribution, as illustrated in a comparison of the two images below:

Even Weight Distribution

The weight is evenly distributed among all columns in this image, and the Percent Null is visible for each of these k-anonymized columns.

Even though the weight of the c_birth_year column has been changed to 97, the value in Percent Null remains the same.

Increasing the weight of a column that is already well-disclosed (like c_birth_year in the example above) will not change the outcome. Generally, the biggest impact will be seen when you increase the weights of the largest Percent Null column. (The only exception to this is if that column already has a lot of native nulls in the remote database.)

For example, shifting the weight to the column c_birth_day (which has a large percent null in the example above) creates a bigger impact on the Percent Null:

## Expert Determination

Like Policy Adjustments, project owners can use Expert Determination to increase a data set's utility while retaining the amount of k-anonymization that upholds de-identification requirements. With this feature enabled, users can redistribute the noise across multiple columns of a data source within a project to make specific columns more useful for their analysis.

While Policy Adjustments are available on all equalized projects with a noise reduction purpose applied, Expert Determination is only available on projects with Re-identification Prohibited.HIPAA De-identification or Re-identification Prohibited.Expert Determination purposes applied, since Expert Determination is specific to the HIPAA De-identification Global Policy.

Once a policy has been adjusted, Expert Determination provides a downloadable report that contains a statistical analysis of the data source to assess the very small re-identification probability indicated by the purpose.

Navigate to Adjust a Policy for a tutorial.

## Keep Fields in the Clear

This feature provides an Allow Fields in the clear option in the create purpose modal, permitting specified analysts to bypass k-anonymization in specific circumstances.

When any purpose with the Allow Fields in the clear property enabled is approved for use within a project, a project member can proceed through the policy adjustment workflow and specify columns to be unmasked. However, the seeded purpose Re-identification Prohibited.Expert Determination.DUAM is specific to HIPAA Expert Determination and automatically has the Show fields in the clear functionality enabled.

Navigate to Adjust a Policy for a tutorial.

### Keep Fields in the Clear Example

Consider the following example, which illustrates a data source whose function column has been selected to be In the Clear and whose gender column remains k-anonymized:

When a user queries this data source while acting under the project, the function column will not be k-anonymized; instead, they will see unaltered values while gender column remains k-anonymized.

Query Results in Project

The function column is in the clear, since the user is acting under the project.

Query Results Outside Project

The function and gender column are both k-anonymized, since the user is not acting under the project.