Subjective Probability
This term is kind of funny because it's a fancy-sounding way of saying that you are guessing the probability of an event.
Author Archives: hangtime
Complement of an Event
Like complementary angles, complementary events complete each other, or at least add up to 1. So that's pretty good.
Independent vs Dependent Events
These are a couple more terms that mostly come up in the explanation for stats word problems, mostly so that you can use the multiplication and addition rules.
Mutually Exclusive (Disjoint) Events
Disjoint events and mutually exclusive events are the same thing. Mostly you'll see this in the setup of a probability word problems, along with the words "assume the events are independent".
Sample Space
This video explains how to write out the sample space of a given trial or experiment, and how to make sure that you're capturing them all. Examples include flipping coins (think tth, tht, hhh, etc) and rolling two dice (11, 15, 36, etc).
Simple Events
Yet another vocab word which every professor and book seems to cover yet you won't see ever again. If you haven't already, definitely watch the Events & Outcomes video first.
Trials, Outcomes & Events
This video clears up the confusion about outcomes and trials, and how to identify one vs the other. It also gets into the nuts and bolts of how to list out the possible outcomes of a situation -- like flipping three coins or rolling two dice -- quickly in a test situation.
This chapter covers so much probability vocab! Besides everything on the list, we've got exciting synonyms as well, like: mutually exclusive events, false positives, independent events and dependent events.
Modified Boxplot
Outliers got your whiskers looking a little long? Afraid the fences are getting too far out? Modified boxplots to the rescue, where you shorten up your whiskers and instead plot the outliers as dots out on the periphery.
Interquartile Range (IQR)
There are lots of ways to define what an outlier is, other than a "way out there". This video introduces the boxplot version -- using the inter-quartile range (IQR) -- which is unique in that you don't need a histogram or standard deviation to do it.
Boxplots On Your Calculator
Hey, who doesn't like to use their calculator to do their Stats homework?! The usual caveats apply of course -- window settings, x-scl, understanding what the heck your calculator is going -- but whether you're doing regular box-and-whisker diagrams or the fancy "modified" version, your TI is there for you.
Intro to Boxplots
This is a quick video which explains all the vocab of box-and-whisker diagrams: whiskers, boxes, fences, outliers, etc. A good place to start!
This chapter covers all you could ever want to know about boxplots, aka box-and-whisker diagrams: How to use IQR to to identify outliers and make them part of the "modified" portion of your modified boxplot; How to do it all on your calculator; how to get your roommates to respect your boundaries (you wish).
Quartiles
Quartiles are just a special case of percentile where the percentiles in question happen to be 25, 50, and 75. Unfortunately, that means you'll get burned by all the craziness of reverse percentile problems, but on the bright side your calculator will spit out quartiles with ease!
Percentiles In Reverse: Given a Percentile, Predict The "Cutoff"
This type of problem is the one with all the crazy instructions: "If L is a whole number, take the average of the Lth and L+1th value, but if L is a decimal always round up!" You get the idea. If they give you a list of numbers and ask you where the 60th percentile would be, this video is for you.
Percentiles & Quartiles On Your Calculator
Will your calculator magically tell you the percentile of a value? Not really. Will it tell you the quartiles? You betcha!
Calculating Percentile of a Data Point
This is the "forward" percentile problem, where you're given a list of numbers and asked to find the percentile of a given value. This video covers the trickier wording that sometimes disguises these problems, as well as how to deal with the two most common definitions of percentiles.
Common Percentile Questions (FAQ)
This video introduces percentiles, and covers a few of the most common confusions you'll come across. It also raises the question of which definition your teacher uses, an important question because you don't want to be using a different one than your professor!
Percentiles are kind of funky because you've been hearing about them for most of your academic career, yet it turns out calculating them is a bit more difficult. For one thing, there's more than one definition of how to calculate them, and not everyone agrees! And going backwards -- being given a percentile and then having to calculate the cutoff score -- has even more disagreement. As always, ask your teacher, but this chapter covers the most common method I've come across.
Z-score vs Coefficient of Variation
If your class covers coefficients of variation, there can be a bit of confusion as to how that's different from z-score. Well, it turns out one is for comparing categories -- think apples and watermelons -- as opposed to individual pieces of data.