--- title: Content gap causes slug: '1575' canonical_url: https://docs.coveo.com/en/1575/ collection: coveo-analytics source_format: adoc --- # Content gap causes When an administrator or analyst [identifies a content gap](https://docs.coveo.com/en/1613/), they'll usually want to address it by identifying the root cause. This article lists some of the most common content gap causes. ## Permission issues When [source](https://docs.coveo.com/en/246/) or [item](https://docs.coveo.com/en/210/) [permissions](https://docs.coveo.com/en/223/) are too restrictive, some end users may not be able to find what they're looking for. Ensure that your end users can access the content they should be allowed to see (see [Content security](https://docs.coveo.com/en/1779/) and [Coveo management of security identities and item permissions](https://docs.coveo.com/en/1719/)). ## Misspelled query keywords When an end user submits a [query](https://docs.coveo.com/en/231/) containing one or more misspelled keywords, that query may return no results. To avoid this, you can enable the Query Correction feature, which is also known as _Did You Mean_. See [Query Correction feature](https://docs.coveo.com/en/1810/) for information and limitations. **Example** If an end user types `Instragram` instead of `Instagram` in the search box, the Query Correction feature should correct their misspelling. ![Coveo search: Did you mean feature demo](https://docs.coveo.com/en/assets/images/coveo-analytics/did-you-mean.gif) However, if the misspelled keyword is too far removed from the intended keyword (for example, `Istnagermm`), the feature will likely fail to provide any satisfactory keyword corrections. > **Note** > > Unlike [Coveo Machine Learning (Coveo ML)](https://docs.coveo.com/en/188/) [models](https://docs.coveo.com/en/1012/), the Query Correction feature does **not** learn from end-user behavior [Coveo Machine Learning](https://docs.coveo.com/en/1727/). ## Lengthy queries By default, [basic query expression (`q`)](https://docs.coveo.com/en/178/) keywords are joined using the [`AND` operator](https://docs.coveo.com/en/1814#and). Consequently, when an end user submits a query containing many keywords, the [index](https://docs.coveo.com/en/204/) may not be able to find items matching all of those keywords. [Enabling the partial match feature](https://docs.coveo.com/en/414/) can help the index return results for lengthy queries. **Example** An end user submits the following query from a search box: `How can I update the OS on my Android device` By default, the index would try to find items containing all of those keywords. This will likely yield very few (if any) results. On the other hand, if the recommended partial match settings are being used (that is, `partialMatch`: `true`, `partialMatchKeywords`: `3`, and `partialMatchThreshold`: `35%`), the index converts the query into a partial match expression. This means that any item containing at least four of the original basic query expression keywords (that is, 35% of 10 keywords, rounded up) will match the query. For example, any item containing the `os`, `android`, and `update` keywords will match the query. ## Invalid query syntax The Search API and index expect query expressions to be properly formed in accordance with the [Coveo query syntax](https://docs.coveo.com/en/181/). If advanced query syntax recognition is enabled on a search box, and an end user submits a query containing invalid syntax, that query will likely return no results (see the [`enableQuerySyntax`](https://coveo.github.io/search-ui/components/omnibox.html#options.enablequerysyntax) option of the `Searchbox` component). > **Leading practice** > > Avoid setting `enableQuerySyntax` to `true` on a `Searchbox` component, as most end users typically don't know how to use advanced query syntax. ## Overly restrictive query filters The filters selected by the end user may be too restrictive. For example, the end user may have selected the wrong [tab](https://docs.coveo.com/en/1406/) (which would typically add an unwanted [constant query expression (`cq`)](https://docs.coveo.com/en/179/) to the query), or they may have selected too many values in different [facets](https://docs.coveo.com/en/198/) (which would generate a highly restrictive [advanced query expression (`aq`)](https://docs.coveo.com/en/175/). > **Note** > > The [search token](https://docs.coveo.com/en/1346/) and [query pipeline](https://docs.coveo.com/en/180/) may also be enforcing additional query filters. In your browser developer tools, you can [inspect the constant and advanced query expressions](https://docs.coveo.com/en/1199#inspecting-a-query) being sent from a given search interface to better understand the end-user journey and find a solution. An issue with restrictive query filters may also be a factor when a visit occurs from an external link. **Example** Merchandisers at _Best Tech_ have launched a marketing campaign for their annual spring sale. This has prompted visits from end users who access their search page via an affiliate link. This link contains state sets in the URLs, which result in preselected facet values. These facet values in combination with the queries return results only temporarily. Once the campaign ends, they no longer return results thus creating a content gap. As a solution, a separate search page should be created specifically for this type of scenario. A different [search hub value](https://docs.coveo.com/en/365#set-the-search-hub) should be used to exclude the page from [Coveo Analytics](https://docs.coveo.com/en/182/) and [Coveo ML](https://docs.coveo.com/en/188/). Therefore search relevance and query suggest wouldn't be affected. This would also enable Coveo to create more accurate content gap reports. ## Query pipeline issues [query pipeline rules](https://docs.coveo.com/en/236/) can modify queries, and therefore have an impact on query results. You can add [conditions](https://docs.coveo.com/en/2793/) to your query pipeline rules, but too many restrictions can result in content gaps (see [Manage query pipeline rules](https://docs.coveo.com/en/1791#manage-query-pipeline-rules-and-models)). In your browser developer tools, you can leverage the `executionReport` to troubleshoot query pipeline-related issues (see [Troubleshooting query pipeline rules](https://docs.coveo.com/en/2088/)). ## Missing content The keywords entered by an end user may not match any available content in your index. Perhaps the content the end user would need exists, but doesn't include the searched keywords. On the other hand, the index may contain no items that are actually relevant to this query. If the content is missing because it wouldn't be relevant for your business, or for the majority of end users, you can typically ignore the reported content gap. However, if further analysis indicates that a significant number of end users are looking for the missing information, you may want to consider adding this content to your index.