User`s guide

confint

4-91

Example Fit the census data to a second-degree polynomial. The display for fresult

includes the 95% confidence bounds for the fitted coefficients.

load census

fresult = fit(cdate,pop,'poly2')

fresult =

Linear model Poly2:

fresult(x) = p1*x^2 + p2*x + p3

Coefficients (with 95% confidence bounds):

p1 = 0.006541 (0.006124, 0.006958)

p2 = -23.51 (-25.09, -21.93)

p3 = 2.113e+004 (1.964e+004, 2.262e+004)

Calculate 95% confidence bounds for the fitted coefficients using confint.

ci = confint(fresult,0.95)

ci =

0.0061242 -25.086 19641

0.0069581 -21.934 22618

Note that the fit display and the array returned by confint present the

confidence bounds using slightly different formats. The

fit display mimics an

n-by-3 array where n is the number of coefficients, the first column is the

coefficient variable, the second column is the fitted coefficient value, and the

third column is the lower and upper bound.

confint returns a 2-by-n array

where the top row contains the lower bound and the bottom row contains the

upper bound for each coefficient.