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Analyzing the level of performance of a sprayers boom suspension or the improvement made with the addition of an automatic spray-boom height controller has traditionally been a qualitative visual observation of the user in various field conditions. The visual observation method provides only a judgement that is based on the individual making the observation. Height data can be collected from the non-contact sensors of a height controller but the difficulty is to analyze this data in an objective manner and to provide a relative quantitative measure of the boom height performance. This paper presents the Hockley Index which is a method for providing a score to the height control performance of the height control based on a statistical analysis of the time the spray boom spent in relation to the target spray height. The more time the spray-boom spent near the target height the higher the Hockley Index score; inversely the more time spent away from the target height the lower the score. The Hockley Index presents a quantitative measure of performance that can quickly be understood by technical and non-technical individuals. The data presented by the Hockley Index can be used as a method for evaluating changes that have been made to the boom height controller or mechanical changes made to the sprayer boom. The Hockley Index can be used with or without automatic boom height control for comparing different boom configurations, different controller settings and for demonstrating the advantages of automatic boom height controllers.