> ## Documentation Index > Fetch the complete documentation index at: https://api.globalwebindex.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # Working with Multiple Data Sets The Spark API and MCP provide access to GWI's full suite of syndicated data sets, scoped to your subscription. This guide covers the key behaviors to know when querying across multiple data sets so you get accurate, efficient results. ## **Our syndicated offer includes two types of data sets** | Data set type | Description | | --------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Primary data sets** | GWI Core, GWI USA, and GWI Kids. Each is based on an independent respondent sample. They cannot be combined with each other in a single query. | | **Add-on data sets** | Add-ons extend GWI Core with additional depth on specific topics. Their respondents are recontacted from GWI Core.
Add-ons can be considered child data sets, linked to their original parent GWI Core data set. These can be combined with GWI Core in a single query, but not with each other or with GWI USA / GWI Kids. | ## **Default behavior: GWI Core and add-ons** When you don't specify a data set, Spark defaults searching for insights within GWI Core and all of its add-on studies. This gives you the broadest possible coverage and is the right starting point for most queries. **Rule of thumb:** If you're not sure which data set to use, don't specify one. The default (GWI Core + add-ons) has the most survey coverage of any single selection. ## **Switching to another primary data set narrows your coverage** If you select GWI USA or GWI Kids instead of GWI Core, you're switching to an independent primary data set with no shared respondents with GWI Core. That selection doesn't include any add-ons, so the data universe Spark will be searching is narrower. | **Selection** | **What's included** | **Coverage** | | ------------------ | ----------------------------- | -------------------------- | | GWI Core (default) | GWI Core + all add-on studies | **Broadest (recommended)** | | GWI USA | GWI USA only | Narrower, US-focused | | GWI Kids | GWI Kids only | Narrower, topic-specific | ## **Spark picks the data set, so help it pick the right one** Spark uses natural language to decide which data set to query. When your prompt could match multiple data sets (for example, 'sports' exists in both GWI Core and GWI Sports), Spark's selection can be unpredictable. Be explicit in your prompts when you want data from a specific data set. | **Instead of...** | **Try...** | | ------------------------------------ | ---------------------------------------------------------------- | | "Give me insights on sports habits" | "Give me insights on sports habits using the GWI Sports dataset" | | "What do people think about gaming?" | "Using GWI Gaming, what do people think about gaming?" | ## **Querying a specific add-on data set directly** You don't need to query all of GWI Core just to access an add-on. Because add-on respondents are a subset of GWI Core respondents, you can select a specific add-on like GWI Work or GWI Gaming directly and still apply GWI Core-based audience filters. **Example:** "Give me insights on gaming habits using GWI Gaming". You can still apply a saved GWI Core audience (e.g. 18-34 males) as the base, because GWI Gaming respondents are a subset of GWI Core respondents. ## **Saved audiences and data set compatibility** Audiences built using GWI Core data points are compatible with GWI Core and any of its add-on studies. They are not compatible with GWI USA, GWI Kids, or any other primary data set, as these have entirely separate respondent pools. If a user applies an audience built using GWI Core to a non-compatible data set query, Spark will return an error. Make sure your prompt templates guide users toward compatible selections. Currently the saved audiences endpoint is search-based and not browse-based. To find your audiences, you need to enter a keyword; asking "what audiences do I have?" won't return a full list. For the most comprehensive results, search by topic instead: "what audiences do I have related to social media?" ## **The data set list is now much larger** The `list_datasets` tool previously returned a handful of options. It now returns the full suite of syndicated studies you have access to in your subscription. This has practical implications: * **Context window:** The full list consumes significantly more tokens. Call `list_datasets` once per session and reuse the result. Don't call it on every turn. * **Filtering:** Where possible, filter by category before passing the list downstream. Avoid sending the full unfiltered payload into a prompt. * **User-facing responses:** When surfacing available data sets to users, group them by type (Core, add-ons, USA, Kids) rather than listing everything flat. ## **Combining data sets: the compatibility rules** Not all data set combinations are valid in a single query. The underlying rule is: you can only combine data sets that share a respondent pool. * Add-ons can be combined with Core. Their respondents are a subset of Core. * Primary data sets (Core, GWI USA, GWI Kids) cannot be combined with each other. * Two add-ons cannot be combined with each other. They don't share a direct respondent overlap. **If you hit a compatibility error:** Check whether the data sets being combined share a parent-child relationship. If you're unsure, use the Core default which handles all of this automatically. ## **Quick reference** | **Situation** | **Recommendation** | | ---------------------------------------------------- | -------------------------------------------------------------------------------------------------------- | | I want the widest coverage | Use the default. Don't specify a data set. | | I want US-only data | Specify GWI USA explicitly in your prompt. | | I want a specific topic (gaming, work, travel…) | Name the add-on data set directly in your prompt. | | Spark is picking the wrong data set | Be explicit: "using GWI Sports, give me insights on…". | | Saved audience isn't working with a primary data set | Check where the audiences come from.
Core-built audiences only work with GWI Core and its add-ons. | | My `list_datasets` payload is too large | Call it once, cache the result, filter before passing downstream. | | I'm getting a data set combination error | The data sets used don't share a respondent pool.
Use one or the other. | | I can't find my saved audiences | Search by topic keyword, not browse the full list. |