# Month: November 2019

## Fractions vs. Decimals: Pros and Cons

Last time, we looked at what fractions are, and saw that fractions and decimals are two different ways to handle numbers less than 1 (or between integers). Here, we’ll look at several questions about why we need both forms, and whether one is better than the other. The comparison and contrast turns out to be …

## Fractions: What Are They, and Why?

We’ve looked at some specific ideas about fractions (their proper definition, their relationship to decimals, and how to divide them); it’s time to go through this topic from the beginning. Here we’ll look at how they are introduced to beginners, and how to keep them from hurting our brains! Parts of a whole Although, as …

## Rank of a Binary Number

(A new question of the week) A few months ago, I wrote about Ranking a Word Among Its Permutations, that is, finding where a word would be found in an ordered list of all possible “words” made by permuting its letters. The problem in general requires a (sometimes lengthy) algorithm. A month or so later, …

Last time, we looked at the basic definition of independent events. This time I want to explore some deeper questions about the concept. Independence by the numbers We’ve seen that, informally, we think of independent events as not affecting one another’s probabilities. Mathematically, though, independence is defined by the fact (which is implied by that …

## What Are Independent Events?

The concept of independent events can be both very simple and easily misunderstood. We’ll be looking at several explanations of the idea, starting with the basics and then digging into some deeper questions that are often overlooked. What is independence? We can start with this question from 1998, asking for the basics: Independent and Dependent …

## Cumulative Distribution Functions (Ogive)

(An archive question of the week) We’ve been looking at some issues involving frequency distributions and the classes used in them. Let’s look at a related concept with some similar issues, namely the cumulative distribution function (CDF), also called an ogive (more on that name at the end of the post!). What is an ogive? …

## Grouped Data: Open-ended Classes?

(A new question of the week) A recent question raised a different issue about grouped frequency distributions than we have discussed previously: What do you do when the last class is labelled something like “30 or more”? As we’ll see, there is no one right answer! An open question Here is the initial question, which …

## Mean and Standard Deviation of Grouped Data

Two of our most-viewed posts deal with Mode and Median of Grouped Data: how to calculate these statistics for data that is supplied in the form of frequencies for classes of data (bins), rather than the individual data values. Here we’ll complete that topic with a look at the less troublesome cases of Mean and …