Reviewer's report
Title:Family history of cancer on survival of patients with gastrointestinal cancer
in northern Iran, using frailty models
Version: 2Date:25 April 2011
Reviewer: Hans C. van Houwelingen
Reviewer's report:
The paper has much improved , but I am not fully satisfied yet.
Major.
1. The survival graphs shown in the response to my previous review should be
included in the paper, because they are clinically much more relevant than all the
residual plots.
2. The paper is biased against the Cox model. The violation of the PH
assumption might be there, but there are similar assumption underlying the other
models that are note tested. Adding a frailty term could remedy the violation of
the PH assumption. Moreover, the baseline hazard of the Cox model would show
a similar humor in the hazard, I presume.
3. The paper is biased in favor of frailty models. Parameter estimates in frailty
models are hard to interpret because they condition on the unobservable frailty.
The effects on marginal survival matter and not those on the conditional survival
given the frailty.
The issues 2. and 3. do not require additional analysis, but they would require
some changes in the text to correct the biased pesrpectives.
Level of interest: An article of limited interest
Quality of written English: Acceptable
Statistical review: Yes, and I have assessed the statistics in my report.
Declaration of competing interests:
I declare that I have no competing interests
Reviewer's report
Title:Family history of cancer on survival of patients with gastrointestinal cancer
in northern Iran, using frailty models
Version: 2Date:25 April 2011
Reviewer: Hans C. van Houwelingen
Reviewer's report:
The paper has much improved , but I am not fully satisfied yet.
Major.
1. The survival graphs shown in the response to my previous review should be
included in the paper, because they are clinically much more relevant than all the
residual plots.
2. The paper is biased against the Cox model. The violation of the PH
assumption might be there, but there are similar assumption underlying the other
models that are note tested. Adding a frailty term could remedy the violation of
the PH assumption. Moreover, the baseline hazard of the Cox model would show
a similar humor in the hazard, I presume.
3. The paper is biased in favor of frailty models. Parameter estimates in frailty
models are hard to interpret because they condition on the unobservable frailty.
The effects on marginal survival matter and not those on the conditional survival
given the frailty.
The issues 2. and 3. do not require additional analysis, but they would require
some changes in the text to correct the biased pesrpectives.
Level of interest: An article of limited interest
Quality of written English: Acceptable
Statistical review: Yes, and I have assessed the statistics in my report.
Declaration of competing interests:
I declare that I have no competing interests
Please review this paper.
user
Reviewer's report
Title:Family history of cancer on survival of patients with gastrointestinal cancer
in northern Iran, using frailty models
Version: 2Date:25 April 2011
Reviewer: Hans C. van Houwelingen
Reviewer's report:
The paper has much improved , but I am not fully satisfied yet.
Major.
1. The survival graphs shown in the response to my previous review should be
included in the paper, because they are clinically much more relevant than all the
residual plots.
2. The paper is biased against the Cox model. The violation of the PH
assumption might be there, but there are similar assumption underlying the other
models that are note tested. Adding a frailty term could remedy the violation of
the PH assumption. Moreover, the baseline hazard of the Cox model would show
a similar humor in the hazard, I presume.
3. The paper is biased in favor of frailty models. Parameter estimates in frailty
models are hard to interpret because they condition on the unobservable frailty.
The effects on marginal survival matter and not those on the conditional survival
given the frailty.
The issues 2. and 3. do not require additional analysis, but they would require
some changes in the text to correct the biased pesrpectives.
Level of interest: An article of limited interest
Quality of written English: Acceptable
Statistical review: Yes, and I have assessed the statistics in my report.
Declaration of competing interests:
I declare that I have no competing interests
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