LinearFitInterval

Advanced Analysis Library Only

AnalysisLibErrType LinearFitInterval (double arrayX[], double arrayY[], double weight[], int numberOfElements, int intervalType, double confidenceLevel, double slope, double intercept, double upperBound[], double lowerBound[], double *deltaSlope, double *deltaIntercept);

Purpose

Calculates the confidence interval for the best linear fitting function or the prediction interval for the observations. The confidence interval refers to the interval within which the actual function is expected to fall. The prediction interval refers to the interval within which the arrayY values are expected to fall in repeated measurements.

Parameters

Input
Name Type Description
arrayX double-precision array The x value of the data set (x, y).
arrayY double-precision array The y value of the data set (x, y).
weight double-precision array The weight of each data point. If weight is NULL, the function assumes all the weights are 1.
numberOfElements integer The length of arrayX, arrayY, and weight.
intervalType integer The type of interval. intervalType must be one of the following values:
  • CONFIDENCE_INTVL (0)
  • PREDICTION_INTVL (1)
deltaSlope and deltaIntercept are not referenced if intervalType is PREDICTION_INTVL.
confidenceLevel double-precision The level of certainty for the confidence interval or prediction interval. For the confidence interval, confidenceLevel specifies the probability that the actual function lies within the confidence interval. For the prediction interval, confidenceLevel specifies the probability that the arrayY values lie within the prediction interval in repeated measurements. confidenceLevel must be between 0 and 1.
slope double-precision The slope of the fitted linear model calculated using the Least Square method.
intercept double-precision The intercept of the fitted linear model calculated using the Least Square method.
Output
Name Type Description
upperBound double-precision array The upper bound for the confidence interval or prediction interval.
lowerBound double-precision array The lower bound for the confidence interval or prediction interval.
deltaSlope double-precision The uncertainty radius of slope. deltaSlope is available only when intervalType is CONFIDENCE_INTVL.
deltaIntercept double-precision The uncertainty radius of intercept. deltaIntercept is available only when intervalType is CONFIDENCE_INTVL.

Return Value

Name Type Description
status AnalysisLibErrType A value that specifies the type of error that occurred. Refer to analysis.h for definitions of these constants.