DEFINITION of 'Longitudinal Data'
The process of collecting sample observations from a larger population over a given time period. Longitudinal data is used in statistical and financial studies.
INVESTOPEDIA EXPLAINS 'Longitudinal Data'
The process of analyzing past return data for a given security is an example of using longitudinal data. By collecting daily, weekly or monthly return data, a financial analyst can determine past return trends, and calculate the stock's value at risk (VaR) using the historical method.
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RELATED FAQS

Where can I find historical stock/index quotes?
There is no shortage of internet sites that provide current stock quotes. Just about any large financial portal will let ... Read Full Answer >> 
What is the variance/covariance matrix or parametric method in Value at Risk (VaR)?
The parametric method, also known as the variancecovariance method, is a risk management technique for calculating the value ... Read Full Answer >> 
What is backtesting in Value at Risk (VaR)?
The value at risk is a statistical risk management technique that monitors and quantifies the risk level associated with ... Read Full Answer >> 
How much variance should an investor have in an indexed fund?
An investor should have as much variance in an indexed fund as he is comfortable with. Variance is the measure of the spread ... Read Full Answer >> 
Can the correlation coefficient be used to measure dependence?
The correlation coefficient can be used to measure the linear dependence between two random variables. The most common correlation ... Read Full Answer >> 
How do you calculate variance in Excel?
To calculate statistical variance in Microsoft Excel, use the builtin Excel function VAR. Given a set of numbers value1 ... Read Full Answer >>
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