ROCS – a simple tool to assess the career status of research optometrists

The scientific output of a researcher can be characterised by the h-index – a single numeric that combines the notions of quantity (number of papers published) and quality (number of citations to papers). Essentially, the index h is defined as the number of papers with citation number > h.¹ For example, a researcher with h-index of 50 has published 50 papers which have been cited at least 50 times. Based on this concept, I developed – together with colleagues in Canada, the UK and USA – the Global Optometrist Top 200 Research Ranking (T200),² which lists the leading 200 research optometrists in the world, in rank order of Scopus h-index. This ranking list is also available on a website which automatically updates every 24 hours (www.optomrankings.com).

In his original paper proposing the h-index, Hirsch¹ noted that for a given individual, h should increase approximately linearly with the number of years that the individual has been publishing papers, and that this should hold quite generally for scientists who produce papers of similar quality at a steady rate over the course of their careers. In the context of the T200, this observation of Hirsch¹ points towards a means of directly comparing the performance of early to mid-career research optometrists, who have been publishing, say, for < 20 years, with senior optometrists who may have been publishing for ≥ 20 years.

Relation between Scopus h-index and year span of publications

As Hirsch¹ was a physicist, his considerations of the meaning of h related primarily to the field of physics. To determine if Hirsch’s expectations of the increase in h over time applies to research optometrists, I extracted data from the T200 extended optometrist research ranking database² (n = 539 optometrists) relating to (a) Scopus h-index (h_s), and (b) year span of publications (YSP), defined for a given optometrist as the year span between the year of the first and most recent research publications recorded on the Scopus database.

In conducting this analysis, I excluded (a) 48 optometrists who commenced publishing in or before 1970, and (b) 7 optometrists who have published any papers as part of the ‘Global Burden of Disease Study’ (GBDS).³ The reasons for these two exclusions are explained below under the heading ‘Caveats’. This extended listing therefore comprised 484 optometrists, forming a data set which was used to determine the relation between h_s and YSP (Figure 1).

Figure 1. Relation between Scopus h-index vs. year span of publications (YSP). The solid line is the line of best fit, and the dashed line is the line of unity.

In Figure 1, the line of best fit (solid line) deviates to some extent from the line of unity (dashed line). For YSP > 15, this deviation increases with increasing YSP values, whereby the line of unity indicates a higher h_s for a given YSP value compared to the line of best fit. It seems reasonable, therefore, to adopt the line of unity is an ‘aspirational measure’ of how h_s advances with YSP in the field of optometry; this assumption also simplifies calculation of current or projected research status, as explained below.

Although the correlation between h_s and YSP is highly statistically significant (p < 0.0001), it is apparent that there is a large spread of data. The r² value of this relationship is low (0.28), meaning that only 28% of the variance in h_s can be attributed to YSP. This suggests that many other factors must be contributing to the h_s of an optometrist, such as differences in the work ethic, productivity and/or scientific excellence of the publications of individual optometrists.

Determining and interpreting the Research Optometrist Career Status (ROCS)

Any research optometrist (even those not listed in the T200) can use the relationship between h_s and YSP to determine his/her research status in relation to career stage, which I shall term the Research Optometrist Career Status (ROCS). The ROCS is simply h_s divided by YSP. That is, that is:

$\mathrm{ROCS}={\mathrm{h}}_{\mathrm{s}}/\mathrm{YSP}$

Hirsch¹ referred to this ratio as the parameter m in his original paper.

The ROCS can be considered as a current measure if YSP ≥ 20, representing established/late career researchers who are more likely to have reached their final destined academic rank. The ROCS can be considered as a predicted measure if YSP < 20, representing junior/mid-career researchers who may not have reached their full career potential. Interpretation of ROCS is indicated in Table 1; this is based on the discussions of Hirsch,¹ and my considerations of the career rank and achievements (largely receipt of research awards and prizes) of those in the T200.²

Table 1. Current^a or predicted^b research optometrist career status (ROCS)^c of those continuously publishing largely in the ophthalmic literature.

ROCS^c	Research impact	Academic rank & awards
2.0	Published work has extremely high impact	Distinguished professor;^d recipient of numerous major international research awards
1.5	Published work has very high impact	Full professor; recipient of many research awards
1.0	Published work has high impact	Full professor; recipient of a few research awards
0.5	Published work has good impact	Assistant Professor/Associate Professor^e

^aFor those with year span of publications (YSP) ≥ 20.

^bFor those with YSP < 20.

^cROCS = h_s/YSP.

^dAlternative titles include University Professor and Scientia Professor.

^eEquivalent to Lecturer/Senior Lecturer.

To understand how this calculation works, consider the following example: an optometrist has a Scopus h_s of 21. This optometrist commenced publishing in 2010, and is still publishing today (2024); therefore, the YSP is 14. Using the above equation, ROCS = 21/14 = 1.5. Given that YSP < 20, Table 1 indicates that this optometrist is currently publishing papers commensurate with that of a full professor who has received many research awards, and predicts a career trajectory – if the current level of activity is maintained – that is likely to culminate in this optometrist rising to the rank of full professor in due course.

Caveats

There are three important caveats in relation to determining ROCS from Table 1. First, Scopus does not count citations of citing papers prior to 1970.² Accordingly, the h_s of an optometrist who published highly cited papers prior to 1970 will be lower than it would have been if pre-1970 citations were counted. Since inclusion of optometrists who commenced publishing prior to 1970 would distort the relationship between h_s and YSP, these optometrists (n = 48) were excluded from this analysis. Figure 1 and Table 1 therefore only relate to those who commenced publishing after 1970.

Second, seven optometrists currently in the T200 publish papers under the auspices of the ‘Global Burden of Disease Study’ (GBDS).³ As explained in detail previously,² many of these optometrists have greatly inflated values of h_s because each of these highly cited papers – mostly published in the high-impact-factor journal Lancet – typically has hundreds of co-authors, meaning that h_s is not truly reflective of the work of an individual. Inclusion of data relating to the seven GBDS-publishing optometrists would distort the regression line in Figure 1; therefore, data relating to these seven optometrists have been excluded. Accordingly, Figure 1 and Table 1 only relate to research optometrists who have not published any GBDS papers. The seven optometrists in the T200 who have published GBDS papers – and any other optometrists publishing GBDS papers now or in the future – need to recalculate their h_s, excluding GBDS papers, to properly assess their current or predicted ROCS from Table 1.

Third, it is assumed that an optometrist has been publishing continuously – largely in the optometric literature – since his/her first paper appeared, at the same level of productivity and quality, without major career interruptions.

Conclusions

The ROCS is a simple tool for determining the current or predicted career status of a research optometrist. In a sense, it normalises the T200 by allowing optometrists to assess their academic career status in the context of the number and quality of research papers they are producing and the time frame over which they have been publishing papers. This tool is likely to be of considerable interest to research-focused optometrists, but perhaps of less interest to optometrists whose interests lie in other areas, such as undergraduate teaching – which is fine, because research is just one of a number of noble career paths that academic optometrists may pursue.

Given the considerable spread of data in Figure 1, the indicated ROCS may not always concur with the actual research standing of an established researcher, or the predicted research standing of an early or mid-career researcher. Consideration therefore needs to be given to possible extraneous factors that may have impacted interpretation of ROCS. For example, a research optometrist may have a lower-than-expected ROCS due to factors that have hampered a steady output of research papers such as career interruptions, or being overburdened with teaching and administration. Conversely, a research optometrist may have an inflated ROCS by virtue of (a) working in a laboratory with a very large number of co-authors generating a prolific output of scientific papers in high-impact medical journals, or (b) publishing largely in a field with a higher research impact than optometry.

For early-career optometrists with a research focus, the ROCS can serve as a source of inspiration and motivation, and for some, confirmation that their research career is on an upward trajectory.