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Linear Regression


In statistics, linear regression is a technique for estimating the relationship between an independent variable, X, and its scalar result, the dependent variable, Y, derived from a series of X-Y relationships.


The computational routine involves trying to fit a straight line between a scatter plot of X-Y coordinates such that the sum of the squared differences between each dependent outcome, Yi, and the line computed at each Xi is minimized. This is the so-called "ordinary least squares (OLS)" estimator.


R-squared, often called the "coefficient of determination," expresses the "goodness of fit" of the line to the scatter plot. It ranges from 0, no fit whatever, to 1, which is a perfect relationship where all the points in the plot fit along the straight line.


The iPad version allows you to add, retrieve, reorder, or delete data sets. It also permits emailing, text messaging, and printing of a PDF report.


   
     



changes in version 7.2
  • New icons for buttons and other controls
  • In iPhone version, double arrows increment or decrement repeatedly if the touch down is held
  • Redesigned the app logo
  • Updated the FaceBook share link syntax
changes in version 6.2
  • Bug fix affecting computation of numerically small X-Y pairs
  • Added correlation coefficient
  • Bug fix affecting iPhone version when loading the first Y value from the stored data with the slider input option
change in version 6.1
  • Fixed bug that prevented adding a new data file without exiting the app
changes in version 6.0
  • iPad version now adds email, text message, and print capability. A PDF report at a resolution of 72 dpi is available for sharing
  • Minor bug fix involving GUI interface
changes in version 5.0
  • Rewritten and redesigned for iOS 7
  • added warning to prevent inadvertent resetting of all data in iPhone and iPad versions
  • GUI enhancements


revised: February 11, 2016