Z scores / alpha

So a question wants to figure out the z critical score. ONline I found a formula: z= 1-(Alpha / 2). Or Z =1-(0.05/2) –> Z=1-0.025 –> Z=0.975. But according to the calculator on the same page, and to answers or others are getting off a chart, the correct answer is 1.645. What gives? I why am I not getting this number?

  1. I’ve found a basic/most common chart that gives the values. But it doesn’t have it for 0.1, which I need. Is it the same as 0.01? I can’t find a chart that goes up to 0.1. Thanks .

submitted by /u/Banjaiel
[link] [comments]

One year of LS430 ownership

Here’s a short “build” progression over the yearNow that I’ve owned my LS430 for a year now I think I can give a pretty good analysis of the car, which we’ve named Old Man Tan.

The numbers: In the past year I’ve owned it I put 24,000 miles on the car (bought it at 63k, now has 87k) drove it from FL to CT, and also from CT to Arkansas and back. I have had to replace was the bank 1 O2 sensor, which of course was original and after 14 years was due anyway. I also sent my ECM out to SIA electronics to get the trans circuitry rebuilt, which may or may have not even been necessary. I have averaged 21 mpg for these 24,000 miles and routinely average 26 mpg on highway trips at 80 mph.

The 4.3 3uz v8 is so smooth you can balance a nickel on it at idle and rev the car to its redline without it falling over. In Drive, say when you’re sitting at a red light, there isn’t a bit of discernable vibration to the point where if you have a cup of water in the cupholder the surface stays completely undisturbed.

I’ve always been a gearhead but this was my first ever Toyota product. I’ve come to admire and respect the engineering behind these cars so much I’ve found myself marvelling at random things as I replace them (read: fix things that aren’t broken). I did the timing belt myself in my garage and Toyota makes it so easy it’s almost foolproof. The oil filter is the same one that’s used in my Ford Ranger and is so easily accessible I can do an oil change in 5 min (not an exaggeration). Interior trim pieces are superbly crafted but held together so simply that my sound system installation was a joke and all the pieces fit back together with no squeaks or rattles.

I have a black ’98 LS400 as well (story for another day) but in my opinion the LS400 and LS430 have to be among the best utilitarian vehicles ever produced. They probably aren’t the best at any single thing but they are competent in everything. There isn’t a single car I’ve ever come across that can last 300k miles easily with basic hand tools and a few spare parts.

submitted by /u/PeaceBay
[link] [comments]

Dirichlet or Dirichlet-multinomial?

I am working with a set of data that consists of a set of products, each with a set of “star” ratings, like Amazon. Each user reviews an item by assigning it a score from 0 to 5; and the dataset is the (nonnegative integer) count of each score for each item.

I am trying to fit a distribution to this dataset for use as a prior in a Bayesian ranking system of these items. Does it make more sense to fit the data to a Dirichlet distribution or a Dirichlet-multinomial distribution?

If I am omitting something (or if you think my thought process is completely wrong), let me know and I will update this post.

EDIT 1: I should note that there is a great degree of variance in the number of reviews for each item; they all have at least 50, but some have over 100 and a few have over 500! Additionally, there seems to be a positive correlation between number of reviews and review score. Just wanted to add this as I felt it was relevant.

submitted by /u/LordBarglebroth
[link] [comments]

Power Inverter Question – 2006 CVPI

Sorry if this is the wrong place to ask, haven’t dove into this side of reddit yet.

I drive a 2006 CVPI and have a laptop set up on the console, I just bought a RIDGID 100W power inverter/adapter to keep the laptop charged. It has an on/off switch, if I turn it off at the end of the night without unplugging it, is it still going to drain my battery? The last couple of days I’ve just been unplugging it, but if it’s possible to leave it plugged in it’d be much easier, as the plug is up and under the console. Thanks!

submitted by /u/saints5468
[link] [comments]

Do you sometimes avoid reading an article on a topic because you know you’ll be stuck doing/understanding the proof of one of the theorems?

I will be attending University in September and plan to major in math. While reading about Galois Theory, for example, I tried to prove the fundamental theorem despite only knowing group theory and the definitions of a field and a vector space. Obviously I failed.

The only instance this has negatively affected me yet is during high school algebra, when I did not use the fundamental theorem of algebra because I didn’t know the proof to it.

Is this kind of a behavior normal for math? How did you get over it? I feel like in University I would be overwhelmed by the number of theorems.

submitted by /u/derlin567
[link] [comments]

Interesting Relationship Between the CFC, Prime Numbers, and the Golden Ratio

So, I have a strange habit of playing around with numbers in Wolfram Alpha for no particular reason, and every once in a while I figure out something mildly interesting. I’m not sure if this relation between the Continued Fraction Constant and the prime numbers exists yet, but:
CFC * PCFC = GoldenRatio seems to hold true, so long as it were possible to actually use all primes for the PCFC, defined as the continued fraction [2; 3, 5, 7, 11…] and so on with the prime numbers. Because I can only use a finite number of primes for obvious reasons, the product between CFC and my approximation of “PCFC” gets closer and closer to the Golden Ratio, but obviously never gets there. Is this something which mathematicians have any use for, was it already discovered, etc?

EDIT: It has been demonstrated through several methods that the ratio only comes out to 99.7% of the golden ratio, and barring any potential limitations on WolframAlpha and other approximations of the math behind this, it seems that the ratio was actually a fluke. Thanks to everyone for helping me out with this.

submitted by /u/CodeReaper
[link] [comments]

Owning a hybrid car has turned me into a worse driver and I regret my decision. Now I want to get rid of this car.

My last car was a 2015 Mustang V6 Convertible. I really wanted a Jaguar F-Type S as my next car, but I drive over 400 miles a week due to work and social obligations. My commute averages about 75 mph because I commute in reverse traffic, so my mpg with the Mustang took massive hits. I was spending up to 2 hours a week at the gas station (Costco lines amirite).

I went in the completely opposite direction and bought a hybrid — a 2019 Hyundai Ioniq. In the first month, I’ve saved over $170 in gas and only refill when I want to. Not once this entire month have I taken a panic detour for gas.

It’s been exactly 31 days since my new purchase. I now want to give this car to my little sister and buy something else that gets at least 30 mpg and has a range of over 400 miles, but isn’t a hybrid, because I can’t do it anymore. I’m not having fun on the road. I have lots of fun when I turn off my car and it shows me my trip mpg, but on the road? It’s abysmal and I feel miserable. My obsession with getting the highest possible mpg has turned clinical.

I deeply regret buying this car because all I do is hypermile. I park my ass in the right-most lane and cruise at a constant 65 mph no matter what is going on. Mind you, if someone is tailgating me, I always let them pass. I never stay in the left or second-to-left lane because I know I’m driving slowly, so I am for sure not a danger to the road. I’m not an oblivious driver.

I’ve tried changing the screens around so I can’t see my mpg or battery usage, but I can’t get it out of my head. When I average over 60 mpg on my trips, my excitement is palpable. There are countless Instagram stories of my fabled 60+ mpg trips. I got almost 63 mpg on a 70 mile trip and still remember the numbers to this day because of how happy I was. I also got exactly 69 mpg on a 13 mile trip that I hold very near and dear to my heart.

Last weekend, I drove my Mustang for about 100 miles with about 18 mpg, and I had a blast. I wasn’t worried about my mpg at all. Everything changes when I sit down in my hybrid. No matter what I try, I can’t drive the way I do with my Mustang, or get the mpg out of my head. It’s not possible, and now I want out.

Let this be a warning to anyone looking to purchase a hybrid vehicle. If you’re at all an obsessive person, perhaps with some type of anxiety disorder, please consult with your psychiatrist or therapist before purchasing a hybrid vehicle.

submitted by /u/lulzcakes
[link] [comments]