> ## Documentation Index
> Fetch the complete documentation index at: https://studies-guides.jaspari.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Eligibility Parameters

> Build inclusion and exclusion criteria from conditions, medications, and structured fields like age or lab values. Learn how ordinary rules and groups combine.

Define who qualifies for your research using conditions, medications, and structured criteria. These eligibility criteria combine according to defined logic rules.

## What you can build criteria from

* **Conditions**: diagnosed conditions and disease history.
* **Medications**: current or prior medication use.
* **Structured criteria**: age, lab values, BMI, prior diagnoses, and other numeric or categorical fields, built with the eligibility rule builder.

Each of these can be used as an inclusion rule (a volunteer must have it) or an exclusion rule (a volunteer must lack it).

## How rules combine

This is the part worth understanding before you add rules. It follows a specific structure:

<Steps>
  <Step title="Ordinary rules of the same type mean 'any one of these'">
    Add Albuterol, Fluticasone, and Symbicort as three ordinary medication rules, with no grouping action taken, and a volunteer qualifies by being on any one of them. The same default applies to condition rules.
  </Step>

  <Step title="Group when you need more than one at once">
    If you specifically need a volunteer on more than one item at the same time, both Drug A and Drug B for example, select those rules and choose "Group rules" then "Match ALL" (this is what the rest of this page calls an **all-of** group, as opposed to the default **any-of** behavior of an ungrouped pool).
  </Step>

  <Step title="Exclusion rules always apply on their own">
    Every exclusion rule stands independently, regardless of how your inclusion rules are grouped. A volunteer who meets even one exclusion rule stays out of the pipeline, no matter what else they match.
  </Step>

  <Step title="Everything is combined together at the top level">
    Your ungrouped medication pool, your ungrouped condition pool, any explicit groups, and your structured criteria (age, lab values, and so on) all have to pass together. A volunteer has to clear every category you've configured.
  </Step>
</Steps>

<Note>
  The rule builder displays a live summary of your configured criteria. This summary reflects the actual matching logic used for volunteer screening.
</Note>

## Adding parameters to a study

<Steps>
  <Step title="Open your study's Screening Questions tab">
    This is where eligibility rules live in the Setup wizard.
  </Step>

  <Step title="Search for a condition, medication, or criterion">
    Results update as you type.
  </Step>

  <Step title="Add it, and set a threshold or range if it's numeric">
    For structured criteria like age or a lab value, set the range or threshold you need.
  </Step>

  <Step title="Group only if you need to require more than one item at once">
    Otherwise, leave rules ungrouped. That already means "any one of these" for conditions and medications.
  </Step>
</Steps>

## Changing eligibility mid-study

You can update eligibility rules any time a study is in draft, active, or paused. Saving replaces your full set of rules with the new one as a complete swap rather than a partial edit, so double-check the complete rule list before saving, including anything beyond the rule you just added.

<Warning>
  Updated rules apply going forward. A volunteer with an eligibility form already open when you make a change will be evaluated against whatever rules are live at the moment they submit, current at that exact moment rather than fixed from when their form was sent.
</Warning>

## Before you can launch

Every rule group needs an explicit any-of or all-of choice set before the study can move out of draft. This check runs once, at launch.


## Related topics

- [Studies Overview](/studies/overview.md)
- [Setup and Launch](/studies/setup-and-launch.md)
- [Launch Your First Study](/getting-started/quickstart.md)
- [Launch, Pause, and Edit a Study](/studies/launching-pausing.md)
- [IRB Library](/compliance/irb-library.md)