# Is there a method to check the homogeneity of variance of a single time series?

I have a data frame with prices/dates, is there a method that checks if the variance is homogeneous during all the series? I know there are many test like fligner.test, bartlett.test but I need to pass to those methods few groups....I don't have groups I have only one series and I need to know if the variance is constant.

Thank you

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 Do you have several prices for a given date? – ocram Nov 7 '11 at 13:24 Is this a time series, in which you wish to check if the variance remains constant over time? – onestop Nov 7 '11 at 13:31 @ocram, no ONE price and ONE date fro about 700 days. – Dail Nov 7 '11 at 13:58 @onestop, Exactly, That's what I am looking for. – Dail Nov 7 '11 at 13:58

the bptest function in the lmtest R package implements the both tests (set studentize=true for the Koenker–Basset test). Looks like it's only for linear models though, so it might not work for your data.