Definition Standard Error Prediction
Contents |
the estimate from a scatter plot Compute the standard error of the estimate based on errors of prediction Compute the standard error using Pearson's correlation Estimate the standard error of the estimate based on a sample Figure 1 shows two regression examples. You can
Standard Error Of Prediction Formula
see that in Graph A, the points are closer to the line than they are standard error of prediction in r in Graph B. Therefore, the predictions in Graph A are more accurate than in Graph B. Figure 1. Regressions differing in accuracy
Standard Error Of Prediction Linear Regression
of prediction. The standard error of the estimate is a measure of the accuracy of predictions. Recall that the regression line is the line that minimizes the sum of squared deviations of prediction (also called the sum of standard error of prediction excel squares error). The standard error of the estimate is closely related to this quantity and is defined below: where σest is the standard error of the estimate, Y is an actual score, Y' is a predicted score, and N is the number of pairs of scores. The numerator is the sum of squared differences between the actual scores and the predicted scores. Note the similarity of the formula for σest to the formula for σ.  standard error of prediction calculator It turns out that σest is the standard deviation of the errors of prediction (each Y - Y' is an error of prediction). Assume the data in Table 1 are the data from a population of five X, Y pairs. Table 1. Example data. X Y Y' Y-Y' (Y-Y')2 1.00 1.00 1.210 -0.210 0.044 2.00 2.00 1.635 0.365 0.133 3.00 1.30 2.060 -0.760 0.578 4.00 3.75 2.485 1.265 1.600 5.00 2.25 2.910 -0.660 0.436 Sum 15.00 10.30 10.30 0.000 2.791 The last column shows that the sum of the squared errors of prediction is 2.791. Therefore, the standard error of the estimate is There is a version of the formula for the standard error in terms of Pearson's correlation: where ρ is the population value of Pearson's correlation and SSY is For the data in Table 1, μy = 2.06, SSY = 4.597 and ρ= 0.6268. Therefore, which is the same value computed previously. Similar formulas are used when the standard error of the estimate is computed from a sample rather than a population. The only difference is that the denominator is N-2 rather than N. The reason N-2 is used rather than N-1 is that two parameters (the slope and the intercept) were estimated in order to estimate the sum of squares. Formulas for a sample comparable to
The slope and Y intercept of the regression line are 3.2716 and 7.1526 respectively. The third column, (Y'), contains the predictions http://davidmlane.com/hyperstat/A134205.html and is computed according to the formula: Y' = 3.2716X + 7.1526. The fourth column (Y-Y') is the error of prediction. It is simply the difference between what a subject's actual score was (Y) and what the predicted score is (Y'). The sum of the errors of prediction is zero. The last column, (Y-Y')², contains the squared errors of prediction.
1: descriptive analysis · Beer sales vs. price, part 2: fitting a simple model · Beer sales vs. price, part 3: transformations of http://people.duke.edu/~rnau/mathreg.htm variables · Beer sales vs. price, part 4: additional predictors http://www.biochemia-medica.com/content/standard-error-meaning-and-interpretation · NC natural gas consumption vs. temperature What to look for in regression output What's a good value for R-squared? What's the bottom line? How to compare models Testing the assumptions of linear regression Additional notes on regression analysis Stepwise and all-possible-regressions Excel standard error file with simple regression formulas Excel file with regression formulas in matrix form If you are a PC Excel user, you must check this out: RegressIt: free Excel add-in for linear regression and multivariate data analysis Mathematics of simple regression Review of the mean model Formulas for the slope and intercept of a standard error of simple regression model Formulas for R-squared and standard error of the regression Formulas for standard errors and confidence limits for means and forecasts Take-aways Review of the mean model To set the stage for discussing the formulas used to fit a simple (one-variable) regression model, let′s briefly review the formulas for the mean model, which can be considered as a constant-only (zero-variable) regression model. You can use regression software to fit this model and produce all of the standard table and chart output by merely not selecting any independent variables. R-squared will be zero in this case, because the mean model does not explain any of the variance in the dependent variable: it merely measures it. The forecasting equation of the mean model is: ...where b0 is the sample mean: The sample mean has the (non-obvious) property that it is the value around which the mean squared deviation of the data is minimized, and the same least-squares crite
Ana-Maria ŠimundićEditor-in-ChiefDepartment of Medical Laboratory DiagnosticsUniversity Hospital "Sveti Duh"Sveti Duh 6410 000 Zagreb, CroatiaPhone: +385 1 3712-021e-mail address:editorial_office [at] biochemia-medica [dot] com Useful links Events Follow us on Facebook Home Standard error: meaning and interpretation Lessons in biostatistics Mary L. McHugh. Standard error: meaning and interpretation. Biochemia Medica 2008;18(1):7-13. http://dx.doi.org/10.11613/BM.2008.002 School of Nursing, University of Indianapolis, Indianapolis, Indiana, USA *Corresponding author: Mary [dot] McHugh [at] uchsc [dot] edu Abstract Standard error statistics are a class of inferential statistics that function somewhat like descriptive statistics in that they permit the researcher to construct confidence intervals about the obtained sample statistic. The confidence interval so constructed provides an estimate of the interval in which the population parameter will fall. The two most commonly used standard error statistics are the standard error of the mean and the standard error of the estimate. The standard error of the mean permits the researcher to construct a confidence interval in which the population mean is likely to fall. The formula, (1-P) (most often P < 0.05) is the probability that the population mean will fall in the calculated interval (usually 95%). The Standard Error of the estimate is the other standard error statistic most commonly used by researchers. This statistic is used with the correlation measure, the Pearson R. It can allow the researcher to construct a confidence interval within which the true population correlation will fall. The computations derived from the r and the standard error of the estimate can be used to determine how precise an estimate of the population correlation is the sample correlation statistic. The standard error is an important indicator of how precise an estimate of the population parameter the sample statistic is. Taken together with such measures as effect size, p-value and sample size, the e