I’ve done both the Neilsen (a number of times) and Aribitron (once) journals.
The Arbitron was a real pain, because I only listen to the radio in my car and it’s like a 10 minute commute. It took longer to fill out the journal than it did to listen to the radio.
At least one time with the Neilsen books, we just put down the shows we wanted to get good ratings, even if we didn’t watch those shows that week.
As for the accuracy of the Neilson’s, I have to say “Nope, not very”. The first time we were picked I was the major writer-downer and I was maybe 10 at the time. My grandmother and grandfather-- both being Spanish speaking as their first language (plus old) never filled out a damn thing. So whatever ratings they got for Lucha Libre were under-reported.
When it was me and my husband, I did fill a lot in ahead of time because those were the shows we always watched and if any circumstance made us miss our favorite shows, we still wanted them counted. So yeah, not so accurate.
My husband and I did the Nielsen Box thing about 6 years ago. I think they were going for gay households, since up to that time all the families I knew who participated identified as straight. It lasted about a year, the novelty wore off in a week. We watched so little TV it must’ve taken them just a few minutes to screen whatever data got recorded.
We did the diary thing for a week in the '70s. Kind of sucked, though, because it was in July, when basically nothing would matter. Not sure, but it might have been the week of one of the political convention extravaganza things, where that was almost the only thing on the big 3 (out of the 6 or 7 we could get).
We did the diary-for-a-week thing just last year, during Thanksgiving Week.
I got a thing in the mail from them asking us to be a Nielsen family, along with a couple of dollars in cash to indicate they weren’t wasting our time.
I don’t recall what ever came of that. I might have filled out a survey, I might have forgotten to do anything with it. Either way, I don’t watch much traditional TV, being a filthy Millennial who watches most of his video entertainment on YouTube or Amazon Prime.
I know someone who was. I don’t know much but I do know they contacted her saying her kids were watching pornography in the afternoons, turned out it was a room mate who was busted.
My understanding is that there was a box attached to their tv that sent information somewhere.
Decades ago, I got to keep a logbook for Nielsen. It only lasted about two weeks.
I’ve received two brand new dollar bills from them on three different occasions in the past 5-6 years but I’ve never replied or participated. I don’t know why they seem to want me to participate so much but I’m not going to. They’re more than welcome two send me another two dollars if they want to.
Okay, I was a household in the BBM Nielsen panel for Ontario for maybe four years or so, 2008-2012ish. I think they may have picked me because I filled out one of those grocery surveys or something.
I had a little pager thing I could clip to my belt and was supposed to wear as often as possible, a charger for it, and a modem that it used to call home overnight. Apparently there are subsonic signals built into TV shows, and the pager just listens for them and records whatever it hears. And it’s got a motion detector so it can tell when it’s actually being work as opposed to just left out next to the TV.
I got little checks based on how often I was wearing my pager, (around ten bucks on a good month,) and thank-you gift cards for a restaurant on the anniversary of my joining the panel. When I switched from a home phone to a cell phone, they reconnected the land-line so that only their pager could use it.
And then I cut out the cable TV entirely, and they asked me for all their stuff back. 
I’ve done the Nielsen diary thing maybe three times, and the radio equivalent once or twice. I was scrupulously honest with the Nielsen diary, although I did alter my usual viewing habits a bit. I avoided leaving the TV on just for noise, and when I did want background noise and nothing I genuinely liked was on I would select the programming I considered most “worthy”. On at least one occasion this was Plaza Sesamo on the Spanish public television channel. Since I am a non-Hispanic (and non-Spanish speaking) adult without children and don’t normally watch Spanish-language children’s programming this probably wasn’t useful data for Nielsen, but I did truly have Plaza Sesamo on at the time I said I did.
I did a radio diary recently and fudged things a bit. I typically listed to NPR podcasts during my commute, but I logged this as listening to NPR on the radio. The diary had a way to mark that you’d been listening to radio over the Internet, but there didn’t seem to be a way to indicate that you were listening to a recorded podcast and not a broadcast.
(jumps up and down) Me! Me! Me!
Every couple of years, I get a questionnaire in the mail where they want me to fill in my TV and/or radio habits, and I get $5. When I was a kid, we did it a few times and got IIRC 50 cents, back in the 1970s.
BTW, a lot of Nielsen correspondence is in an unmarked envelope. I always open all my mail, even obvious junk mail, because I almost threw away concert tickets some years back :eek: , and the unmarked envelope usually contains two crisp new $1 bills, sent unsolicited. 
Hey, it’s MONEY and I’m not going to throw that away.
Have been a journal keeper a couple of times, just finished having boxes in the house for a year. Basically they just sat next to TV and picked up audio to figure out what you were watching. Pretty easy to forget about until they called because one had shifted six inches and needed to be adjusted.
I did the Arbitron radio survey thing about 20 or so years ago. It was during the summer and I spent much of my time at our college sailing club. I didn’t have a car or even a radio at home. I accurately recorded that VHF-16 was the only radio channel I listened to that week while I was hanging out at the boathouse.
I’ve done the Nielson journal a couple times. Once when I was a teen living at home and once a few years ago. You just have to write down what times you watched TV, what was watched and who watched it. In the recent journal you also report what you DVR. The journal only covered a short period of time. A couple weeks? Don’t remember exactly.
I did the Nielsen journal about 10 years ago. IIRC watching stuff on Tivo didn’t work well with their log format somehow, it was a bit frustrating.
Unless things have changed drastically in the few years since I stopped working in the TV industry they have a combination of meter boxes (in the larger markets like NY, LA, Chicago, etc) and paper diaries in the smaller markets. Those boxes are very expensive so they only put them in the places that demand very accurate and immediate reporting of data.
About 4 or so years ago. I think I made $7 or so from them, in crisp new cash. One “free” payment just for considering it, and some more when I agreed. Paper journal. I don’t watch much TV (and basically zero now unless they’ve started including Netflix and other streaming), so they didn’t ask me back.
I think it’s impossible not to let it alter your habits somehow, even if you are completely honest and don’t claim that you watched only PBS and Firefly.
I was for one week (when I was living alone). I just received something in the mail. Everything had to be recorded in a logbook and then mailed out. The biggest pain about this was that you needed to list your various cable channels–the number with the station–in the book, which was annoying since most of those stations I didn’t watch but I still had to record them (per the instructions provided).
I’ll be honest and say that I did not log anything that I didn’t actually watch or have the TV on for. However, I also watched things I ordinarily wouldn’t have simply because they were shows I wanted to have good ratings (PBS, etc.).
It was fun if a bit time-consuming, but I’ve never been asked to do it again.
My wife an I were picked to do Arbitron, and RIIIIIIGHT after she quit her job . . . …as a radio station newswoman after she didn’t get a promotion she thought she deserved.
Lets just say a couple of the jocks who treated her like shit didn’t get a good book.