# Quintile: Definition, Examples in Economics, Health

Statistics Definitions > A quintile is a 1/5th (20 percent) portion of the whole. In statistics, it’s a population or sample divided into five equal groups, according to values of a particular variable. It can also be used to refer…

# Intention to Treat

RCTs > Intention to treat (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…

# Ljung Box Test: Definition

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…

# Excel PERCENTRANK Function, PERCENTILE & RANK

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…

# Frequency Domain: Definition

Statistics Definitions > Frequency domain analysis refers to analysis where a signal is studied with respect to frequency, rather than with respect to time. The data being studied is plotted with the frequency on the x axis and the amplitude…

# Curve Fitting

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…

# Mediator Variable / Mediating Variable: Simple Definition

Types of Variables > A mediator variable is one which explains the how or why of an (observed) relationship between an independent variable and its dependent variable. In a mediation model, the independent variable cannot influence the dependent variable directly,…

# Primary Data & Secondary Data: Definition & Example

Experimental Design > Primary data is data that is collected by a researcher from first-hand sources, using methods like surveys, interviews, or experiments. It is collected with the research project in mind, directly from primary sources. The term is used…

# Kriging: Definition, Limitations

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…

# You need an expert. We have one for you

It’s midnight and you’ve been working on your homework assignment that’s due tomorrow for the last two hours. You’re stuck on a few problems in your textbook and could really use some extra help. After looking around at the empty…