Artículo de publicación ISIThis correction serves to provide the correct rendering of Table 3 with its respective symbols corrected to superscript (provided below and not in the original article). Additionally with this correction the author would like to bring to attention the revision of the original article, correcting typographical errors in the Abstract, Tables 1, 2, 3 and Figure 7. For the abstract this entailed the changing of ‘productivityon' to simply ‘productivity'. For Tables 1, 2 and 3, this entailed the changing of “five” to “four”. And for Fig. 7 this entailed changing the footnote from “at the five of the SSI” to “at the five stations of this study”.