Error-tolerant search: Getting results even with incorrect entries

What does fault tolerance mean?

As part of the international guidelines for human-computer interaction EN ISO 9241, error tolerance is particularly important in the area of website usability. According to Part 110 of EN ISO 9241, a dialog is "error-tolerant if the intended work result can be achieved with either no or minimal correction effort on the part of the user, despite recognizably incorrect input."¹ In other words, error tolerance ensures that the user can still get the desired search result even if they enter the wrong information in the search field of a website, e.g., an online shop. An error-tolerant search should not only respond to typing and spelling errors, but also allow other spellings, singular and plural forms, and synonyms.

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Step by step toward ideal fault tolerance

First of all: there is no universal setting for error tolerance. The ideal error tolerance range varies depending on the online shop. If, for example, it is a specialized online shop, i.e., one with a comparatively small but very similar product range, the search should definitely be sensitive to typos. If there is no error tolerance or it is insufficient, the user may quickly end up on a so-called zero-hit page, meaning that no matching search results are displayed.

Fault tolerance controller in the epoq Control Desk

The problem here is that for most users, an unsuccessful search is reason enough to abandon the current search altogether or continue it in another online store, which means you could lose potential sales.

Example of an error-tolerant search

In order to keep the bounce rate as low as possible, the error tolerance should be individually tailored to the requirements of your online shop. The following applies: the higher the error tolerance range is set, the more sensitively the search responds to incorrect entries. However, a range that is too low or too high should always be avoided. Why? We'll show you with an example:

• If the user searches for the term "rock" with a low error tolerance, but accidentally enters "Rcok" in the online shop's search function, they will be taken directly to a zero-hit page, increasing the risk that they will quickly leave the website.
• However, if the user enters the same search query ("rock") with too high an error tolerance, results for the term "sock" could also be displayed, for example, since at least 3 of the 5 letters match the actual search query. It is questionable whether the search results for "sock" are relevant to the user at all.
• If the online shop carries both skirts and socks in its product range, the relative error tolerance can also be used to easily set whether and to what extent other, less relevant products should also be displayed in the search results.

Error tolerance in the epoq demo shop

As you can see, error tolerance should always be adapted to your individual requirements in order to provide customers with the best possible support when searching your online store. With the help of our practical error tolerance control, you can easily determine for yourself in the Control Desk how sensitively your intelligent search should react to entered errors.

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Conclusion: Reduce bounce rates simply by using a fault-tolerant search

To ensure that customers get the right results despite incorrect entries in the onsite search, you should never do without an intelligent search function in your online shop. After all, if your customers find what they are looking for straight away, it not only increases their satisfaction and your chances of making a sale, but also the amount of time they spend in your online shop.

Source: ¹ Usability Handbook