Search.assistivedata.com is the address of a fake search engine. This means that it is incapable of producing any search results on its own and instead redirects the user's search queries through a legitimate engine - Google, in this case. Users do not land on fake search engines such as Search.assistivedata.com on their own usually. Instead, they are taken there through forced redirects caused by browser hijacker applications and extensions.
Search.assistivedata.com is not an exception and it has been observed to be promoted by the SearchModule browser hijacker. Typically, these applications are programmed to take over certain browser settings and set them to open the promoted address. Almost always they include the homepage, new page tab, and the default search engine of the browser. Furthermore, while the browser hijacker is present on the device, it will prevent users from changing the affected settings back to their original state.
It must be noted that conducting searchers through a fake engine opens users to security risks such as having unrelated, third-party advertisements being injected into the results even if they do no match the search criteria. The advertisements could redirect to dubious websites or landing pages for technical schemes or offers designed to manipulate users into downloading and installing PUPs (Potentially Unwanted Programs).
If you are seeing Search.assistivedata.com on a regular basis, it is strongly recommended to scan your device with a reputable anti-malware solution and then remove all suspicious applications that are detected.