Outlier treatment
This paper mentions a mechanism to clean high frequency data of outliers. The setting is NYSE TAQ(Trades and Quotes data) and many initial filters(data cleaning) applied are specific to NYSE. However the mechanism for removing outliers that is mentioned by is market agnostic. The key idea behind the method is to choose k neighbor prices + a fudge factor gamma, and compute a trimmed mean and standard deviation of the k neighboring prices.