In UX design, a hypothesis predicts a design's outcome. A UX hypothesis refers to the expectation of how users will interact with the product or its elements, e.g. "with a search bar on a website, the users will easily find the information they need". The hypotheses are usually validated through user testing, A/B testing or other validation methods.
Why are hypotheses so useful? First of all, they serve as a foundation for making evidence-based decisions about design and user experience. Having a hypothesis and checking it allows UX designers to make their decisions depending on data, not intuition. Hypotheses can also help measure the project's success by comparing the outcome with the well-defined hypothesis from the beginning (the original prediction). They also decrease experimentation costs and allow for faster iteration. The team can formulate and test chosen hypotheses which helps determine what works and needs improvement. This leads to faster design adjustments, making the entire process more efficient. Ultimately, all that results in a better user experience as it was regularly optimised to meet the user's needs and goals.
When formulating a hypothesis, you want to make sure it's useful, and there are a few things to do to accomplish that. Firstly, your hypothesis should be specific and testable, clearly describing the expected outcome. If possible, formulate it based on already existing data to avoid making impossible assumptions. The hypothesis should also be clear and understandable to everyone involved in the project.
There are also certain things to avoid. For example, your pre-hypothesis assumptions shouldn't be detached from reality but based on existing research and data. You also shouldn't make the hypothesis overly complicated – don't use complex or convoluted language. Last but not least, avoid making untestable hypotheses. If your hypothesis can't be tested or validated through research or data analysis, you should change it into one you can. Otherwise, it simply isn't useful.
A well-defined hypothesis is a testable prediction that guides the product design process and leads to more informed and user-centred design decisions.