Regression and correlation 346 the independent variable, also called the explanatory variable or predictor variable, is the xvalue in the equation. This is because during the development of the software, we must ensure that. Ocw offers a snapshot of the educational content offered by jhsph. Multiple linear regression and matrix formulation introduction i regression analysis is a statistical technique used to describe relationships among variables.
Statistical learning theory winter 2016 percy liang last updated wed apr 20 2016 01. The dependent variable depends on what independent value you pick. Regression is a procedure which selects, from a certain class of functions, the one which best. A scatter plot is a graphical representation of the relation between two or more variables. Often you can find your answer by doing a t test or an anova. There are many possible answers, including to increase con. Sxy x x xy y 64 the estimated covariance is sxy n 1 65. In the scatter plot of two variables x and y, each point on the plot is an xy pair. Regression testing should be performed on all software changes. Regression testing any failed execution must yield a test case.
Amount of testing performed must be balanced against the cost of undiscovered errors. Retest previously tested element after changes, to assess. Some notes will be written during the exploratorytesting session, so that a report. We begin with the numerator of the covarianceit is the \sums of squares of the two variables. Lecture notes in computer science computer science and. So, what is an overview of todays lecture, i will introduce you to what is. However can show that in the 2 variable case the variance of the iv estimator is given by where r xz2 is the square of the correlation coefficient between endogenous variable and.
Principles of imperative computation william lovas lecture 19 march 24, 2011 1 summary we begin with a discussion of the question, why do we test our code. Topics testing basics partition testing measure test quality unit testing and test driven development. Csc 408fcsc2105f lecture notes these lecture notes are. Hansruedi kunsc h seminar for statistics eth zurich february 2016. Pdf regression testing is a part of the software testing activity, which is an. Regression analysis allows us to estimate the relationship of a response variable to a set of predictor variables.
A large part of software testing costs is spent by various regression testing activities. The defect should be resolved in the normal course of development activities. Ocw materials are not for credit towards any degrees or certificates offered by the johns hopkins bloomberg school of public health. Pdf a study for regression testing techniques and tools. Pdf regression testing in an industrial environment. Notes prepared by pamela peterson drake 1 correlation and regression basic terms and concepts 1. I the simplest case to examine is one in which a variable y, referred to as the dependent or target variable, may be. Lecture notes on testing carnegie mellon school of. Regression testing means to confirm that a recent program or code change has not adversely affected existing features. The independent variable is the one that you use to predict what the other variable is. Bertrand meyer, michela pedroni eth zurich, february.
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