Birthday Paradox


When it comes to probability and statistics, I figure most of that is a left-brain function and I’m pretty much mostly in my right mind. Consequently, with me it all becomes a guessing game. Last Sunday at church, a lady named Janet asked: “Did you see the flower beds?” How could I not? We were both standing outside not twenty feet away from one of them. So was she fishing for a compliment? Janet is the person that painstakingly has planted, cared for and maybe even prayed that the flowerbeds would flourish. Whatever she’s done, it is working. They look fantastic!


Honestly, it has been an amazing transformation. Janet has a green thumb, but she seemed a little distraught. Pointing to the beds she asked: “Did you notice the tracks?” The General says that I don’t pay attention. Maybe she’s right. Until the Janet mentioned tracks, I hadn’t noticed the layers of mulch surrounding the plants were uniformly uneven. Something obviously had been in the flowerbed.


I asked, “So do you think it was deer?” I’ve never thought about it before now, but the term deer can be used as either singular or plural. The use of the term can mean either. For that matter, the same is true of the word fish or sheep. I guess technically adding “s” to the word deer is grammatically correct, but I’ve never heard it done. The term deers sounds strange rolling around in my head.


So for that matter, my left-handed suggestion that the culprit invading the sanctity of the flowerbed was a deer was way off-track (pardon the pun). Janet shook her head “No”. She didn’t believe for a moment that deer or deers was or were responsible. Until the sound of the word “armadillo” rolled off the tip of her tongue, I was at a loss. Once she mentioned armadillo, I intuitively knew that Janet was right. She’s the kind of gal you’d want to take tracking with you. I’d be absolutely no help in coming up with the right answer.


Just so you know that I have a destination in mind for my morning (late morning blog – I’m retired now) , I wondered about the term beer. Is beer singular or plural? I don’t know the answer, but regardless of the number, I don’t want any. I tasted beer in college and learned it is obviously an acquired taste. I guess the same is true of whiskey mixed with Kool-Aid. I tried that in college as well and found it equally unpalatable .


With that as a backdrop, you’ll probably be surprised to know that I invited the General to go with me to happy hour yesterday. Why not, from 3:00 – 7:00 p.m. through the workweek, Jack Allen’s has a 50% off special on their appetizers. I had no interest in the beer (for that matter, I don’t know if the happy hour discount applies to that or not), but the chunky Queso is a tasty bargain at that price.


Besides that, the 3:00 – 7:00 discount is available to anyone ordering an appetizer. It is not reserved as a senior discount. Did I mention, I don’t look for opportunities to cash-in on a senior discount? A retired friend suggested that we meet at McDonalds for coffee with the notation that the coffee is free for seniors. Thanks but no thanks! While I’d enjoy the coffee and the conversation, I’m not a fan of McDonalds. I don’t need access to the playground. Besides that, Mazama Coffee Company is the “happening place” in Drippin’ to meet for coffee. I’m not going to become one of those old man who hang out anywhere for a free this or that just because I’m old. Thanks, but no thanks!


So the General and I made it into Oak Hill for happy hour at Jack Allens yesterday afternoon. Miracle of miracles, we even found a place to park. I’m hearing impaired and I didn’t fully catch the name of the waiter? Consequently, I repeated “Keith” back to him. Is that spelled with a “k” I asked. All I heard was the “eith”. He smiled and repeated his name back to me. He added, whenever I tell anyone my name over the phone, they think I’ve said: “Pete”. I really try to enounce it clearly. That was good enough for me, “I promised to call him Keith unless I messed up and called him Charles. He laughed and said, “If you get confused, just ask for the guy with the beard.”


I later noticed two other waiters through the window on the patio who had beards, so I called Charles (I mean Keith) to task. He smiled and said: “I’m the only waiter working inside that has a beard”. That led to a discussion of the “birthday paradox”. Keith mentioned that he learned about the birthday paradox from one of his college professors. I, too, went to college, but maybe that was before the “birthday paradox” was a topic for discussion. I was clueless.


So Keith asked: “How many people do you need to have in a room before you have a 100% chance that someone else in the room has the same birthday? Maybe I had a puzzled look on my face. He added: “This is the easy one.” Since I had been eating Queso and not drinking beer, I didn’t blurt out an answer. Consequently, Keith answered his question for me. He was right. It was a simple answer: “366 people in the room.”


It didn’t take long for the birthday paradox to get a little over my head. All you have to do is throw out the term “bell curve” and I’m out of the game. By-the-way, Keith used the term. However, he couldn’t remember the exact answer for the number of people needed in a room for there to be a 99.9% chance that two people would have the same birthday. He threw out the number 32 and I was at a loss. Go figure, I can’t. That is a left-brain function.


It later occurred to me that I now know why Keith is serving Queso in a restaurant and not working the numbers game. He was wrong about needing only 32 people to have a 99.9% chance of two people having the same birthday. If you believe what you can find on Google, you need 75 people in the room to have a 99.9% chance. Of course, you reportedly only need 23 people in a room to have a 50% chance.


For me to sort it out, I’d have to be hardwired differently. I’m not going to waste my brain power looking for the answer. The one thing I know for sure is that the General and I shared the Queso and we got twice as much. So now you’re confused. You thought I said it was 50% off. It was, but it was so good that we opted to order a second order. Consequently, we ended up getting twice as much, but for the regular price.


All My Best!