Reviewer's report 
 Hepatocyte growth factor (HGF) in fecal samples: rapid detection by surface plasmon Title: 
resonance 
 2  18 February 2005 Version: Date: 
 Michael Pearce Reviewer: 
Reviewer's report: 
The results generated by the experiments are surface plasmon 
resonance signals and optical density readings from ELISA. Both types of data are continuous but may well not be normally distributed. The authors appear to have taken a conservative 
approach and used non-parametric statistical techniques which is 
sensible. 
The numbers of patients and controls in the study is small. This 
can result in inadequate statistical power, but the authors seem 
to have achieved a number of statistically significant results 
which suggests that statistical power is not a major issue. 
However, with small numbers, results are inherently unstable and 
it would be useful if the authors could give some indication of 
just how variable results for PSR and ELISA were by tabulating 
results. Because of the small sample size, selection biases may 
also be important determinants of results in this study. 
In RESULTS, para 1, the authors state that patients with 
gastroenteritis had significantly higher signal responses compared with patients with colon cancer or normal controls. 
They should say what statistical technique they used to come to 
this conclusion. 
The authors demonstrate a correlation between SPR and ELISA 
results for patients with gastroenteritis. However, as a rule of 
thumb, one should have 10 or more points for regression lines/curves. Figure 3 does not meet this criterion. 
The use of the Friedman test and Wilcoxon test to assess the 
effects of altering the immobilization levels is appropriate. 
In Figure 1, the confidence limit for SPR readings for samples 
from patients with colonic cancer is <0. 
The authors concede in the DISCUSSION that the number of 
observations is small but then state they have results of 
significance from another study with 70 patients. Why not 
combine the results for a much more robust paper? If there is some urgency about reporting results from the smaller study, I think it would be appropriate for the authors to consider a 
letter or small communication format, and submit a more formal 
paper later with results from both studies. 
Reviewer's report 
 Hepatocyte growth factor (HGF) in fecal samples: rapid detection by surface plasmon Title: 
resonance 
 2  18 February 2005 Version: Date: 
 Michael Pearce Reviewer: 
Reviewer's report: 
The results generated by the experiments are surface plasmon 
resonance signals and optical density readings from ELISA. Both types of data are continuous but may well not be normally distributed. The authors appear to have taken a conservative 
approach and used non-parametric statistical techniques which is 
sensible. 
The numbers of patients and controls in the study is small. This 
can result in inadequate statistical power, but the authors seem 
to have achieved a number of statistically significant results 
which suggests that statistical power is not a major issue. 
However, with small numbers, results are inherently unstable and 
it would be useful if the authors could give some indication of 
just how variable results for PSR and ELISA were by tabulating 
results. Because of the small sample size, selection biases may 
also be important determinants of results in this study. 
In RESULTS, para 1, the authors state that patients with 
gastroenteritis had significantly higher signal responses compared with patients with colon cancer or normal controls. 
They should say what statistical technique they used to come to 
this conclusion. 
The authors demonstrate a correlation between SPR and ELISA 
results for patients with gastroenteritis. However, as a rule of 
thumb, one should have 10 or more points for regression lines/curves. Figure 3 does not meet this criterion. 
The use of the Friedman test and Wilcoxon test to assess the 
effects of altering the immobilization levels is appropriate. 
In Figure 1, the confidence limit for SPR readings for samples 
from patients with colonic cancer is <0. 
The authors concede in the DISCUSSION that the number of 
observations is small but then state they have results of 
significance from another study with 70 patients. Why not 
combine the results for a much more robust paper? If there is some urgency about reporting results from the smaller study, I think it would be appropriate for the authors to consider a 
letter or small communication format, and submit a more formal 
paper later with results from both studies. 
Please review this paper.
user
Reviewer's report 
 Hepatocyte growth factor (HGF) in fecal samples: rapid detection by surface plasmon Title: 
resonance 
 2  18 February 2005 Version: Date: 
 Michael Pearce Reviewer: 
Reviewer's report: 
The results generated by the experiments are surface plasmon 
resonance signals and optical density readings from ELISA. Both types of data are continuous but may well not be normally distributed. The authors appear to have taken a conservative 
approach and used non-parametric statistical techniques which is 
sensible. 
The numbers of patients and controls in the study is small. This 
can result in inadequate statistical power, but the authors seem 
to have achieved a number of statistically significant results 
which suggests that statistical power is not a major issue. 
However, with small numbers, results are inherently unstable and 
it would be useful if the authors could give some indication of 
just how variable results for PSR and ELISA were by tabulating 
results. Because of the small sample size, selection biases may 
also be important determinants of results in this study. 
In RESULTS, para 1, the authors state that patients with 
gastroenteritis had significantly higher signal responses compared with patients with colon cancer or normal controls. 
They should say what statistical technique they used to come to 
this conclusion. 
The authors demonstrate a correlation between SPR and ELISA 
results for patients with gastroenteritis. However, as a rule of 
thumb, one should have 10 or more points for regression lines/curves. Figure 3 does not meet this criterion. 
The use of the Friedman test and Wilcoxon test to assess the 
effects of altering the immobilization levels is appropriate. 
In Figure 1, the confidence limit for SPR readings for samples 
from patients with colonic cancer is <0. 
The authors concede in the DISCUSSION that the number of 
observations is small but then state they have results of 
significance from another study with 70 patients. Why not 
combine the results for a much more robust paper? If there is some urgency about reporting results from the smaller study, I think it would be appropriate for the authors to consider a 
letter or small communication format, and submit a more formal 
paper later with results from both studies. 
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