This cookie policy is regularly reviewed and updated.
It was last reviewed in February 2024.

What are cookies?

Cookies are small data files that we store on your phone, tablet or computer when you visit our website. We use these for record-keeping and to improve your experience on our website. You can deactivate cookies by changing the settings in your web browser.

How we use cookies

We use some cookies to make the website work, and we call these ‘essential cookies’. Other cookies allow us to enhance the experience.

  • Essential cookies. These are required for our website to function, and to allow visitors to use some of the features.
  • Analytics cookies. These allow us to understand how people find and use our website. This helps us to improve our participant recruitment and the website experience.
  • Functionality cookies. These allow us to recognise you when you return to our website and personalise content for you, for example by remembering your preferences.

Below is a list of the individual cookies we use on and

CookieTypePurposeHow long do we keep these cookies?
_researcher_portal_sessionEssentialStores session dataUntil you close your browser
_pk_testcookieEssentialUsed to check whether the visitor’s browser supports cookiesWe do not keep these cookies
_pk_ses, _pk_cvar, _pk_hsrEssentialUsed to temporarily store data for the visit30 minutes
_pk_refAnalyticsUsed to store referral information for the visitor’s first visit the website6 months
_pk_idAnalyticsUsed to store details about the visitor such as the unique visitor ID13 months
ofh_utmAnalyticsUsed to store referral information about website visitors​Up to 1 year.
Cleared on sign up / login.
mtm_consentEssentialUsed to store consent for analytics, provided by the visitor1 year, unless revoked by user
cookie_consent_refusedEssentialUsed to store if the user has declined the use of analytics cookies1 year
MATOMO_SESSIDEssentialHelps prevent CSRF security issuesWe do not keep these cookies
_csrfEssentialHelps prevent CSRF security issuesWe do not keep these cookies

We aim to meet the highest standards of data privacy and use Matomo to analyse the use of our website. Matomo does not require that we share analytics data related to your activity with any third parties and enables you to opt out of tracking.

Browsing without Javascript?

We use Javascript for most of our cookies. If you have Javascript turned off in your browser, we will only capture essential cookies so you won’t have the option to turn cookies on and off.

Have questions?

If you have any questions about our use of cookies or other technologies, please email