Significance Limit for Autocorrelation

Significance Limit: The limits for the ACF (and PACF ) at the stated Significance Level, if the true population ACF (or PACF) is zero. ACF (or PACF) exceeding this value should be investigated and assumed non-zero.

where k is the ordinate of the normal distribution at the stated Significance Level (determined using tables of the Normal distribution found in any statistical quality control textbook) and n is the number of observations included in the analysis.

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