The chi-square statistic (χ2) is a measure of the difference between the observed and expected frequencies of the outcomes of a set of events or variables.

Chi-square is useful for analyzing such differences in categorical variables, especially those that are nominal in nature.

χ2depends on the size of the difference between actual and observed values, degrees of freedom and sample size.

χ2 can be used to test whether two variables are related or independent of each other.

It can also be used to check the correspondence between the observed distribution and the theoretical frequency distribution.

Non-linearity is a mathematical term that describes a situation where the relationship between the independent variable and the dependent variable cannot be predicted along a straight line.

The Poisson distribution, named after the French mathematician Siméon Denis Poisson, can be used to estimate how many times an event can occur within “X” time periods.

The posterior probability in Bayesian statistics is the revised or updated probability of an event occurring after new information has been taken into account.

Unconditional probability reflects the probability that some event will occur without taking into account any other possible influences or previous results.

The 90/10 retirement investment strategy involves investing 90% of investment capital in low-cost S&P 500 index funds, and the remaining 10% in short-term government bonds.

The chief operating officer (COO) is the senior officer tasked with overseeing the day-to-day administrative and operational functions of the business.