Statistics How To

Types of Variables > What is a Lurking Variable? A lurking variable is a variable that is unknown and not controlled for; It has an important, significant effect on the variables of interest. They are extraneous variables, but may make the relationship between dependent variables and independent variables seem other than it actually is. In … Read more

Hierarchical Clustering > What is Agglomerative Clustering? Agglomerative clustering (also called (Hierarchical Agglomerative Clustering, or HAC)) is a “bottom up” type of hierarchical clustering. In this type of clustering, each data point is defined as a cluster. Pairs of clusters are merged as the algorithm moves up in the hierarchy. The majority of hierarchical clustering … Read more

Types of Graph > A Lorenz curve is a graph used in economics to show inequality in income spread or wealth. It was developed by Max Lorenz in 1905, and is primarily used in economics. However, it may also be used to show inequality in other systems. The Gini index can be calculated from a … Read more

Probability > In probability, a set of events is collectively exhaustive if they cover all of the probability space: i.e., the probability of any one of them happening is 100%. If a set of statements is collectively exhaustive we know at least one of them is true. These types of events or statements may or … Read more

Statistics Definitions > The Gini coefficient is a statistic which quantifies the amount of inequality that exists in a population. The Gini coefficient is a number between 0 and 1, with 0 representing perfect equality and 1 perfect inequality. Sometimes these statistics are reported in terms of percentages, with numbers between 0 and 100. It … Read more

RCTs > Intention to treat analysis (ITT analysis) is a method of statistical analysis often used in medical research. In ITT analysis, a study participant is analyzed as belonging to whatever treatment group he/she was randomized into, whether or not the treatment course was completed as intended. Reasons Behind Using Intention To Treat Analysis Intention … Read more

Autocorrelation > The Ljung (pronounced Young) Box test (sometimes called the modified Box-Pierce, or just the Box test) is a way to test for the absence of serial autocorrelation, up to a specified lag k. The test determines whether or not errors are iid (i.e. white noise) or whether there is something more behind them; … Read more

Excel for Statistics > How to use the Excel PERCENTILE function, PERCENTRANK function and RANK function Contents: PERCENTILE / PERCENTRANK RANK Excel PERCENTILE function and Excel PERCENTRANK function: Overview Watch the video or read the steps below: Update 09/02/2016: The video is for Excel 2013; The steps for Excel 2016 are exactly the same. Excel … Read more

Trend Analysis > Curve fitting is the way we model or represent a data spread by assigning a ‘best fit‘ function (curve) along the entire range. Ideally, it will capture the trend in the data and allow us to make predictions of how the data series will behave in the future. Types of curve fitting … Read more

Regression Analysis > Kriging is a type of regression that gives a least squares estimate of data (Remy et. al, 2011). It uses z-scores to generate an estimated surface model from the spatial description of a scattered set of data points. It originated in mining geology, and is now an important part of the geostatistics … Read more