Sure, your company invests the time of many people in the process. But you do it because you've determined that overall it adds value to have another employee. It's worth the cost. Hopefully, most things that they would otherwise be doing if not searching for a candidate would also add or maintain value of some sort (whether monetary or not). So really, it's just another value adding task that must be done. So we've established that in the end you gain more value by having that employee than it costs to hire them.
From the employee perspective they may or may not actually be looking for a job, versus casually interested in all possibilities (like me). They also may or may not already have a job, in which case they'll have to take the day off to go through such an extensive interview, giving away work and potentially IP for free.
If I have a job and/or I'm not really desperate, then the cost of the interview may be greater to me than what I see as the potential gain. Especially when compared with the other possibilities out there. There are a lot of companies that will pay for any significant amount of time spent coding for an interview. Why would I waste my time with a company that doesn't value my time (esp. taking it off work), the work they're asking me to do, or potentially the IP I give them (e.g. if I come up with a new way of looking at a problem or a new solution they haven't thought of during the code interview).
A couple hours is a reasonable sacrifice, IMO, but may depend on each candidates situation. If I as asked to spend more than 2 hours coding, I would ask for compensation or turn down the interview.
Someone else said that it wasn't a good use of a developers time to give up a day for interviews because the potential return wasn't good enough. I completely accept that. My take is that, in the market I operate in at least, spending a day doing an interview with someone who isn't really that interested probably isn't the best use of my time either.
If you're casually interested the aim shouldn't be to do a day long technical interview, it should be to establish what the real level of interest is and to either build that interest or establish that it's the wrong thing for you / us. Once we've done that we're either in a situation where you're keen on the role and we're looking at something where a day might be a good investment for you, or we've saved us both a day.
Making a significant time investment when one party isn't serious about the opportunity is the wrong thing to do for both company and candidate, and throwing money at the problem doesn't change that.
Ultimately I'd like to show you I value your time by not wasting it, rather than by paying for it if that makes sense?
I absolutely agree. I think that it's important to first establish interest and weed out candidates that are obviously unqualified. You can figure a lot of that out in a short amount of time. While some of your best candidates may already be employed and thus only casually interested initially, at least for someone like myself that interest could increase significantly after sitting down and chatting about the company and projects for a bit. If I were to then become really interested it could be worth spending a lot more time in an interview process.
Personally I don't think that a company will learn much more from 8 hours or more than they could learn in 3-4 hours tops though. I think it's overkill in most situations.
From the employee perspective they may or may not actually be looking for a job, versus casually interested in all possibilities (like me). They also may or may not already have a job, in which case they'll have to take the day off to go through such an extensive interview, giving away work and potentially IP for free.
If I have a job and/or I'm not really desperate, then the cost of the interview may be greater to me than what I see as the potential gain. Especially when compared with the other possibilities out there. There are a lot of companies that will pay for any significant amount of time spent coding for an interview. Why would I waste my time with a company that doesn't value my time (esp. taking it off work), the work they're asking me to do, or potentially the IP I give them (e.g. if I come up with a new way of looking at a problem or a new solution they haven't thought of during the code interview).
A couple hours is a reasonable sacrifice, IMO, but may depend on each candidates situation. If I as asked to spend more than 2 hours coding, I would ask for compensation or turn down the interview.