Does the H index have predictive power?

Abstract

Bibliometric measures of individual scientific achievement are of particular interest if they can be used to predict future achievement. Here we report results of an empirical study of the predictive power of the h index compared with other indicators. Our findings indicate that the h index is better than other indicators considered (total citation count, citations per paper, and total paper count) in predicting future scientific achievement. We discuss reasons for the superiority of the h index.

Fig. 1.

h index vs. time (left scale) and total number of citations (N_c) vs. time (right scale) for E. Witten (theorist) (a) and M. Cardona (experimentalist) (b). The dashed and dash-dotted lines show linear and quadratic fits to the h index and N_c, respectively.

Fig. 2.

Scatter plots of total number of citations, N_c, after t₂ = 24 yr vs. the value of the various indicators at t₁ = 12 yr (t measured from the date of the first publication). h, h index; N_p, number of papers; n_c, mean number of citations per paper; r, correlation coefficient, with r = 1 corresponding to perfect linear correlation.

Fig. 3.

Predictive power of each indicator at time t₁ = 12 yr for the value of the same indicator at time t₂ = 24 yr for sample PRB80.

Fig. 4.

Predictive power of each indicator at time t₁ = 12 yr for the number of citations to papers published in the t₁ − t₂ time interval, with t₂ = 24 yr, for sample PRB80.

Fig. 5.

Predictive power of each indicator at time t₁ = 12 yr for the value of the same indicator for the papers published in the t₁ − t₂ time interval, with t₂ = 24 yr, for sample PRB80.

Fig. 6.

Predictive power of each indicator at time t₁ = 12 yr for the number papers published in the t₁ − t₂ time interval, with t₂ = 24 yr, for sample PRB80.

Fig. 7.

Predictive power of each indicator at year 1994 for the number of citations to papers published in the 1995–2006 time interval, for sample APS95.

Fig. 8.

Predictive power of each indicator at year 1994 for the value of the same indicator for the papers published in the 1995–2006 time interval, for sample APS95.

Fig. 9.

Predictive power of each indicator at year 1994 for the number of citations to all papers published up to 2006, for sample APS95.

Fig. 10.

Predictive power of each indicator at year 1994 for the value of the same indicator at year 2006, for sample APS95.

Fig. 11.

Correlation coefficient, r, between N_c(t₁, t₂) and h_α defined in Eq. 2, for samples PRB80 and APS95. As α increases, the curves approach the asymptotic values given by the dashed lines, r = 0.53 and r = 0.43, respectively.