Maria Rosala is the Director of Research at Nielsen Norman Group. She leads and oversees research at NN/g, trains teams around the world on UX topics, and works with clients to help them improve the user experience of their products and services.
Usability testing and other UX evaluation methods can be divided into two major categories: formative evaluation and summative evaluation. Both have their place, but at different stages in the design lifecycle, and they have different characteristics, for example in the number of test participants needed for a good study.
