1 Introduction  
2 The Arecibo Legacy Fast ALFA Survey  
2.1 Data selection  
3 Methodology  
3.1 Transforming the heliocentric frame of reference  
3.2 The Skewness test  
3.3 Distance dependence analysis  
3.4 Distance errors and the Monte Carlo method  
4 Results  
4.1 Results of the Skewness test  
4.2 Results of distance dependence analyses  
4.3 Bulk ﬂow velocity with ALFALFA  
5 Conclusions and Final Remarks