Getting an onsite is totally cause for celebration! But don't start planning your move yet!

So you've made it passed your initial phone tech screens and you've been invited for an on-site; or maybe you're so good that they just invited you straight to an on-site (a supreme resume you must have!) - congratulations! I wish I could say you're half way there, but that depends on the company.

There's a lot at play with an on-site interview. For your interviewer, they are looking for:
(1) If they like you as a person and if you mesh with your co-workers (culture-fit)
(2) Were those tech screens a fluke?
(3) How are you going to increase company revenue, meaning YOU specifically.

For you, you have TWO jobs! Don't mess this up!
Tech-wise, you need to:
(1) Demonstrate those tech screens weren't a fluke
(2) Come in with a game plan on how you're going to contribute to company profit

but because you're so good, you need to evaluate the company for yourself so when you have multiple offers, this means you have a plan on how to choose. You need to:
(A) Check out the office space - do you see yourself working there?
(B) Find out who your manager would be - do you feel comfortable talking to them?
(C) How big is the team? Do you like the team members? (if this answer is no, abort immediately)
(D) Be confident and start asking about benefits and potential salaries. They actually want/expect you to do this, and it looks like you aren't interested if you don't
(E) Is the team growing? Are you replacing someone or is yours a new spot? Where will you sit?
(F) Ask directly and confidently about any concerns you might have (i.e. How many meetings do you all have? Why are there are so few women here (esp good question if you're male)? )

You're courting them, but remember, they asked you to the onsite because they want you too!

At this point, we're going to split into three categories: top tier tech companies (i.e. Facebook, Google, Amazon), start-ups, and large companies without the tech name power (i.e. McDonalds, Nike, etc.). These companies all want data scientists but have different goals for what their data scientists will do and thus different approaches to the on-site. Quick summaries:

Top tier tech (TTT): Yeah, you need to impress here. The culture fit matters but only if you've demonstrated you're brilliant and what they are hiring you to do. It pays here to figure out in your phone tech screen what exactly they are hiring you to do ("Ah, you want me to be an natural language processing expert. I should study that then..."). The "how-you-feel" about the company doesn't matter to them a whole lot - the attitude is somewhat "you're lucky if we deign to offer you a position" and, hey, you probably are because you're competing against thousands of people and they are going to offer you a great salary. They are not looking for you to evaluate them in the A-F list. You're also least likely to get the job after an onsite here - these companies are notorious for bringing maybe 10 people in for an onsite planning only to keep 1. You're still very much competing for a spot here.

Flexibility = start up key, so it's a good idea to ask yourself if you're actually flexible or trying to get a job that you don't actually want?

Start-ups: Polar opposite of the TTTs - they desperately need great people who work well with others and can immediately come in and make the company money. For the really small start ups, they can't offer you a whole lot in benefits and salary, but they can offer you stimulating and dynamic work and a feeling of importance - you matter a whole lot to them. For people coming from ego-crushing graduate school, this might feel something like a dream come true ("my work matters!!"). They are specifically looking for you to have a plan ("here's what I can do for you") and they are looking for the A-F list: your attitude can make or break company productivity and they can't afford a bad hire. You also probably got the job if they invited you to an onsite here (they can't afford mistakes!) so really focus on the A-F.

Big Name Non-Tech: These companies are somewhere in between. You may be one of their first data scientists or you may be joining a team of 10, but they have the financial reserves to pay you well and put you up for a great long-term career. In many ways, these companies embody the best of the start up and high power tech world - you're kind of treated like a person (sometimes bound by corporate logistics) but you're paid awesomely and you can plan for a 10 year career with some awesome benefits. Sweet! However, your onsite is going to be all over the place; they want that A-F culture fit questioning, but they also may ask you software engineering questions outside your expertise as a data scientist. These companies may or may not know how to hire for a data scientist, but showing enthusiasm, preparedness, and an understanding of product is a make-or-break here.

So how you approach your onsite depends on what company you're on-siting for. No matter what company, it's going to be a long day. Like a kindergartener, you're going to need to ask for water and bathroom breaks. If they are a kind company, they'll feed you too.

Guaranteed that you'll be writing on a white board at some point, but what I found interesting was that it was usually self-initiated - "Do you mind if I start working on this here?". Keep things logical and well organized if you're white boarding. A good tip is to organize things into columns: IDEA | CODE | PURPOSE. That's killing two birds with one stone - keeping it easy for you to keep progressing and showing your interviewers that you are a structured individual when solving problems (great!).

Don't be scared! You're even closer to getting a job now!

Like the tech screens, don't fear the on-sites. In most cases, this means they like you and want to hire you. If they don't, it's not usually because you didn't do a good job, it just isn't the right job for you. Try not to get disheartened or feel cheapened by rejections - there are so many companies out there and you might not have fit into the specific little box they needed to fill. If I've learned anything in this process, it's that there is a job out there for you, but you have to keep your chin up to find it.

Another personal admission is that I was personally terrible at asking the companies the A-F list. Don't do this!!! Be confident! You're going to hate yourself when you're trying to do it on the phone later and making a decision because recruiters are telling you that you have 6 hours and you find yourself saying "You didn't tell me I'd have 3 weeks of vacation?! That makes a huge difference". Learn from my mistakes - ask these questions on the onsite, it's better for EVERYONE! Companies can't guess what are the make-or-breaks for you, and if they decide to offer you a job, they want to know those ahead of time!