Quoting time and effort for UX research

Question

Edit : I've added a little more detail to the main question here.

There are many techniques and practices at our disposal to gain an understanding of the target audiences motivations and needs when using a website or application. These can of course be carried out face to face, remotely or even undercover but all need to be done.

In your experience how long does it take for you to

1. Get a reasonable amount of information to base personas and scenarios upon?

Edit : how many interviews from the same demographic or target group would be recommended to base one persona or scenario upon?

Document the findings into deliverables suitable for client use?

How receptive are clients if the effort required is more than they expect?

Answer 1

There's no fixed number or amount of time. The goal of personas is to create a model of people in your demographic so that your team and client can focus on, communicate about, and refer back to this representation when making decisions. Ultimately, personas are an aspect of a process called mental modeling. The goal of mental modeling is to understand your users' motivations and contextual decision-making process so you can create interfaces and experiences that match their expectations, and, as a consequence, effectively solve their problems.

The book Mental Models by Indi Young is a good starting point to learn about mental models and will help you determine how "much" is enough to obtain a coherent understanding of your target audience to the extent that your desired model (eg. personas) matches them closely enough that you have "a reasonable amount of information to base scenarios upon".

Related reading you may find useful (if you're a software developer): Domain-Driven Design by Eric Evans which focuses on creating a model of the business goals by attempting to understand the "domain" you're designing for. See more at the Wikipedia page on domain-driven design.