Statistics How To

Statistics Definitions > Finite and Infinite Statistics Finite and Infinite Statistics 1. Finite Statistics Finite statistics are statistics calculated from finite sets. Basically, you have a sample that you’re using to make a calculation (like the sample variance). If you have a countable number of data points in your sample, what you end up with … Read more

Regression Analysis > Cox’s proportional hazards regression model (also called Cox regression or Cox’s model) builds a survival function which tells you probability a certain event (e.g. death) happens at a particular time t. Once you’ve built the model from observed values, it can then be used to make predictions for new inputs. The best … Read more

Hypothesis Testing > What is a one sample median test? The one sample median test checks whether or not there is a significant difference between our hypothesized median and the real median of a sample. There are two one sample median tests, the Wicloxon Signed Rank Test and the Sign Test. Both are simple, easy … Read more

Regression Analysis > Y hat (written ŷ ) is the predicted value of y (the dependent variable) in a regression equation. It can also be considered to be the average value of the response variable. The regression equation is just the equation which models the data set. The equation is calculated during regression analysis. A … Read more

Probability > An event space contains all possible events for a given experiment or happening. An event is just a set of outcomes of an experiment, combined with their probability. And an “experiment” has a meaning a little different to the one we use in ordinary speech: it’s anything, with a well-defined set of possible … Read more

Statistics Definitions > Marginal effects tells us how a dependent variable (outcome) changes when a specific independent variable (explanatory variable) changes. Other covariates are assumed to be held constant. Marginal effects are often calculated when analyzing regression analysis results. The marginal effects for binary variables measure discrete change. For continuous variables, they measure the instantaneous … Read more

> Probability > Probability of selecting a person from a group or committee Overview: Problems about picking people from groups or committees are extremely common types of questions in probability and statistics. This article shows you the odds of picking a certain person FROM a committee. If you want to figure out possibilities for choosing … Read more

Probability > Construct a probability distribution Make a probability distribution: Overview A probability distribution is basically a chart of what the probability of an event happening is. It’s a way of quickly viewing the event, and the probability of that event. Probability distribution charts can get quite complex in statistics. For example, a normal distribution … Read more

Normal Distributions > A Box Muller transform takes a continuous, two dimensional uniform distribution and transforms it to a normal distribution. It is widely used in statistical sampling, and is an easy to run, elegant way to come up with a standard normal model. In fact, since it can be used to generate normally distributed … Read more

Descriptive Statistics > A mean plot is a plot which shows the mean, and sometimes also the standard deviation, of data. It’s used to analyze the way in which the mean varies across different groups of data or between samples. Setting up a Mean Plot The vertical axis in a mean plot is typically the … Read more