# How to calculate 95% confidence interval using regression analysis?

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Anwesha Sharma am 24 Feb. 2023
I have a timeseries dataset of measured lengths of some lines. The dataset consists of dates from oct of one year to march of next year. How do I calculate the 95% confidence interval values using regression analysis for each season (e.g. oct 2003 to March 2004 and so on). Something like this as shown below (CI = 95% confidence interval). ##### 2 Kommentare1 älteren Kommentar anzeigen1 älteren Kommentar ausblenden
Anwesha Sharma am 24 Feb. 2023
Thank you so much. This worked perfectly.

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### Akzeptierte Antwort

Sulaymon Eshkabilov am 24 Feb. 2023
If there is a linear fit model for x vs. y(x), then fitlm() can be used, e.g.:
x = (0:.1:13)';
Noise = 35*randn(size(x));
y = @(x)3*x.^2-5*x+3;
Y =y(x)+Noise;
YT=table(x);
YT.Y=Y;
FM =fitlm(YT, 'Y~x^2+x+1')
FM =
Linear regression model: Y ~ 1 + x + x^2 Estimated Coefficients: Estimate SE tStat pValue ________ _______ _______ __________ (Intercept) 5.1654 8.6403 0.59783 0.55101 x -7.3628 3.0713 -2.3973 0.017962 x^2 3.2304 0.22865 14.128 6.7796e-28 Number of observations: 131, Error degrees of freedom: 128 Root Mean Squared Error: 33.5 R-squared: 0.945, Adjusted R-Squared: 0.944 F-statistic vs. constant model: 1.1e+03, p-value = 2.04e-81
plot(FM) ##### 2 Kommentare1 älteren Kommentar anzeigen1 älteren Kommentar ausblenden
Sulaymon Eshkabilov am 27 Feb. 2023

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