Who to ask for recommendation letter

[pecmsyx]

Hi, I am an undergrad double majoring in Stats and Math. I am applying for doctoral program in Statistics this Fall. I am on my third research project. I wanted to ask the professors who worked with me on the projects to write recommendation letters for me. However, my supervisor on my first research project was not a professor nor a faculty member, she is the Research Data Infrastructure Manager at a research department at my school. My first research project was one of many projects in a larger program and the person who oversaw the entire program is a Math professor. He and I did not have as much interaction together but he has been at all of my presentations and my poster session. Who should I ask for the recommendation letter? Would asking a non-faculty work against me?

Would love to hear your thoughts!

[fuzzylogician]

It's better to have a letter from a faculty member. A common solution to a situation like yours is to have your direct supervisor and the professor co-write the letter, or have the supervisor do most of the writing (or create a draft) but then have the professor put in the finishing touches and sign it. That way you get both the benefit of the details from someone who really knows you and of the signature that carries more weight. 

[Edotdl]

On 8/21/2016 at 1:08 AM, fuzzylogician said:

It's better to have a letter from a faculty member. A common solution to a situation like yours is to have your direct supervisor and the professor co-write the letter, or have the supervisor do most of the writing (or create a draft) but then have the professor put in the finishing touches and sign it. That way you get both the benefit of the details from someone who really knows you and of the signature that carries more weight. 

I think this is generally how it's done, even in typical academic lab settings. Usually you aren't working directly with the PI, but rather with a grad student or post-doc. So even though the PI is the one to write the letter, I think they generally ask the grad student/post doc for their insights/details.