public transportation, passes, and fares

[juldea]

So it occurs to me that since the route I take to work involves only the CT1 and the CT2 busses, and they accept both subway and bus passes, it might be cheaper for me to buy a monthly bus pass and pay cash for extraneous subway rides (as opposed to my normal method of buying a subway pass and paying for extraneous bus rides). Let's find out.

Subway pass: $44
I'd say that I fork over $2 (bus roundtrip) 1-2 times a week for odd trips. So we'll assume 6 times per month: $12
Total: $56

Bus pass: $31
I take the subway at least once a week on weekends, and randomly mid-week... so we'll assume the same 6 times/mo, only this time the roundtrips are $2.50: $15
Total: $46

So, yes. The bus pass would be cheaper by $10 a month at my current estimations.

If I settle at 6 bus trips per month, how many times do I have to ride the subway for it to not save me money?
56 > 31 + 2.5x
25 > 2.5x
10 > x

Hmm. We'll have to see if I end up riding the subway more than twice a week, then. And how much I do end up riding non-CT busses, since I have access to them.

It's delight in activities like this that make me wonder if I should really go for a graduate degree in statistics.

Comments

[alexx-kay.livejournal.com]

When doing similar calculations, I found it useful to consider "freedom cost". That is, "If I *don't* have a Foo Pass, will the extra cost of going somewhere on Foo make me less likely to actually go there? And if so, how much do I care about that effect?"

[juldea.livejournal.com]

Heh. The times I take the subway are pretty much all important things I won't stop doing - going to Worcester or the doctor's office, things like that. I suppose the subway also gets me to your house, but that's going to happen less after this week anyway.

But good idea, and I'll keep it in mind. It looks like I'm going to do a lot of data-gathering during the next month regarding my travels. ;)