Get reliable science

The degree of difficulty of the Range Plant Identification Contest has varied over time. To show its evolution a scatter plot with the scores of the first three places per team was elaborated. Data were not complete for all years. For the period 1955-1980 data were obtained for 10 years and for the period 1981 to 2016 data were available for 34 years. There are three distinct stages marked by the years 1983 and 1999. In the stage of 1955 to 1982 the first three places had very similar scores and a reduced degree of dispersion is shown. The first place mean score was 97.89% and the difference between the first and third place means was 2.16 percentage points. In the second stage from 1983 to 1996, scores were reduced, the first place mean score decreased to 95.69%, which is very similar to the third place mean score in the previous stage. The difference between the first and third place mean score increased to 4.66 percentage points. Finally, in the stage from 1999 to 2016 there was a great reduction in the means and a greater dispersion of the grades was shown. The mean of the first place score, 91.99%, was very similar to that of the third place score of the second stage. The difference between first and third place, which was 8.43 percentage points, increased considerably when compared to those obtained in the previous stages. After analyzing the graph and observing the trend lines it becomes evident that the contest has increased its difficulty over time. This increase has been because of the changes on the Contest Rules as well as by the increase of more challenging specimens such as seedlings and barks