Dear Huma!

A few come to my mind:

- Ease and adequacy of the syntax with regard to users' goals and knowledge

- Graceful interpretation of search terms

- Response time of the service and how you handle waiting times

- Feedback on quality of search time

- Real-time suggestions when user enters search term

- Display of search results

-- The information to display: give the user just enough context to distinguish interesting hits

-- Sorting

-- Categorization

- What options are there to refine an existing search?

Hope this helps,

Jan

Jan seift has elaborated nicely and of course ia an exhaustive list which a researcher cab further elborate further but it ultimately leads to effectiveness in information retrieval spontaneoysly.

Thanks @Jan Seifert, these parameters will be helpful.

Thanks @Shafi Sir, in other words, we can say that an effective retrieval system has a user-friendly search interface?? Is it so, Sir???

User friedly-ness is a.dividend to retrieval effectivenees...ultimate goal of a system or its  window  for users to access and discovery...ie interface in my humble opinion.

Thanks agn Sir