Editing Allan variance (section)

===Measurement length and effective use of samples===
Studying the effect on the [[#Confidence interval|confidence intervals]] that the length ''N'' of the sample series have and the effect of the variable ''τ'' parameter ''n,'' the confidence intervals may become very large since the [[#Effective degree of freedom|effective degree of freedom]] may become small for some combination of ''N'' and ''n'' for the dominant noise form (for that ''τ'').

The effect may be that the estimated value may be much smaller or much greater than the real value, which may lead to false conclusions of the result.

It is recommended that:

* The confidence interval be plotted along with the data, such that the reader of the plot knows of the statistical uncertainty of the values.
* The length of the sample sequence (i.e. the number of samples ''N'') must be kept as high as possible to ensure that confidence interval is small over the ''τ'' range of interest.
* Estimators providing better degrees of freedom values be used in replacement of the Allan variance estimators or as complementing them where they outperform the Allan variance estimators. Among those the [[total variance]] and [[Theo variance]] estimators should be considered.
* The ''τ'' range as swept by the ''τ''<sub>0</sub> multiplier ''n'' is limited in the upper end relative ''N'', such that the reader of the plot may not be confused by highly unstable estimator values.