Performance of Small-Scale Sawmilling Operations: A Case Study on Time Consumption, Productivity and Main Ergonomics for a Manually Driven Bandsaw

Round 1

Reviewer 1 Report

Performance of Small-Scale Sawmilling Operations: An Evaluation of Time Consumption, Productivity and Main Ergonomics for a Manually-Driven Bandsaw

The paper is very well structured, easy to read and thoroughly covers the subject.

Abstract

There is lack of the study’s results in the abstract: what was found and why the results are important. The background information should be shortened. It should provide a broad introduction to the field comprehensible to the general reader, and then a sentence of more detailed background specific to the study. This should be followed by an explanation of the objectives/methods and then the results and the main conclusions of the study.

Introduction

The authors undertook a detailed literature review of the published materials on the small-scale sawmilling operations. The review is comprehensive, well organised and cited in an appropriate manner and provides “in-depth” analysis and discussion of the relevant materials. The review presents a very good outline of the research topic and highlights major gaps in the past and current research studies.     

Methodology section is well described, and the rationale for the selection of experimental methods is adequately explained.

The experimental part of the study is extensive and complex. The authors approached this problem in a very knowledgeable manner. The analysis and interpretation of the results have been based on sound statistical methods. The results have been correctly used to draw consequential conclusions and recommendations for future research studies.

Conclusions and implications are adequately developed, clearly linked to the nature and content of the research framework and findings. Future research opportunities have been identified.

Author Response

Dear reviewer 1,

 

we highly appreciate your effort and constructive comments regarding our submitted manuscript. More detailed changes can be seen in the tracked changes of the current manuscript (uploaded as supplementary file).

 

 

Review 1

 

The paper is very well structured, easy to read and thoroughly covers the subject.

 

Abstract

 

There is lack of the study’s results in the abstract: what was found and why the results are important. The background information should be shortened. It should provide a broad introduction to the field comprehensible to the general reader, and then a sentence of more detailed background specific to the study. This should be followed by an explanation of the objectives/methods and then the results and the main conclusions of the study.

Response: Abstract was improved. Thanks

Author Response File: Author Response.docx

Reviewer 2 Report

Overall:

In this manuscript the authors do a work-flow study accounting for productivity and safety (posture and noise) at a single small sawmill operated by between one and three people.  Many of the variables estimated are strongly correlated with one another.

While likely of interest to the readers of Forests, this manuscript has several serious drawbacks.  First, there is no replication (only one sawmill, only one to three operators).  Thus, this is really a case-study.  I don’t believe this precludes publication, but this needs to be written throughout as a case study and not as an experiment or experimental design.  This will also need to be addressed with whatever statistical methods are employed.

Second, the entire paper needs significant revisions for English language and grammar.  Incorrect words are used in some cases.  While technically correct, I don’t think promiscuous is the best word choice to describe the Italian sawmills’ work environment (line 111).

Third, the authors spend too much time discussing sawmilling in general or in an abstract way, and too little time clarifying the importance of this work, and how all the disparate variables (productivity, posture, noise) are linked.  Clearly defined hypotheses, if there were any, could help bring better focus to the intro, results, and discussion sections.

Abstract:

The abstract contains too much introduction and none of the results.  Rebalance it.

Keywords:

Overly generic (mechanization, efficiency, sustainability)

Introduction:

First half of first paragraph is overly generic intro.  Omit.

Line 50 – if inefficient sawmilling is no longer sustainable, then how do small sawmills, which are inherently inefficient, fit it? 

Could streamline the justification for studying small sawmills in lines 69-85.

Line 114 – why simply summarize methods of a study rather than results?  How were their results relevant to this study?

Line 123: Common sense line seems a bit pedantic.  Recommend rephrasing.

Overall the introduction covers relevant literature, but doesn’t highlight what was observed in those studies, or how that lead the authors to their research objective.  Intro needs considerable work.

Were there any hypotheses that were tested?

Methods:

Line 138: need scientific names for these two trees.

So this study is of a single sawmill with only 3 workers?  This basically means that none of the data are replicated.  Collecting multiple days’ worth of data is a form of pseudoreplication.  This study needs to be more clearly described as a case study, which is what it is.  There is no experiment, or experimental design, as there is no true replication.  This should be reflected clearly in the title, abstract, methods, and results sections.  Logs are not the level of replication.  Either the sawmill or maybe the workers are.

TMD should be included in table 1

Line 203: It is unclear if they only used 6 days of noise data, or if they somehow extrapolated the six days of data to predict noise levels for day 7.  Clarify and if the latter more details are required.

Line 214: The postural analysis seems pretty unreliable given that only up to 3 people were observed.  Height of this specific equipment and these specific operators seems like it might heavily influence the results.  The lack of replication makes the broader applicability of these observations pretty dubious.

Line 238: Why does unreplicated data need to be normally distributed?  I’m assuming they simply entered all these data points from different logs or different days, and treated those as different samples.  They are not, since this isn’t an experiment, but rather a case study.  This criticism applies to all the statistical methods described in this paragraph.

Line 268: Need more details than ‘the usual formulae and approaches were used’.

How many operators were these data collected from?  If more than one operator, were differences observed between the operators?  This seems relevant.

Results:

People who are red-green colorblind will not be able to discern P from R in figure 2.  Use different shapes in addition to different colors.

The authors routinely use the word ‘statistics’ to describe data.  Clarify.

The presented postural codes (1 – 7) are never described or defined.  This needs to be done somewhere so the data may be interpreted.

Discussion:

The authors state that analyzing efficiency and safety together are common sense, yet they present these data separately and never really draw any linkages between them.  How are productivity and safety related based on these data?

The discussion seems pretty superficial.  They do provide context with the literature, but it is unclear what the interpretation of these data is.  How are productivity and safety linked?  How might improving productivity alter safety?  What factors (e.g. log size) most influenced the variables measured related to safety?  Did log volume being milled impact noise?  There seem to be a lot of analyses and discussion left on the table that could better tie the manuscript together.

Ancillary:

Should the fact that a co-author owns this sawmill be included in the Conflicts of Interest statement?  The authors felt the need (understandably so) to disclose this in the methods section.

Author Response

Dear reviewer 2,

we highly appreciate your constructive comments and contribution to the genesis of this manuscript. In particular, the first comment helped us to improve the overall quality. We agree that the objective of the current study was not clearly described in the last version of the manuscript. Still, as you can see in the tracked changes of the current manuscript (supplementary file), more modifications were facilitated.

Review 2

In this manuscript the authors do a work-flow study accounting for productivity and safety (posture and noise) at a single small sawmill operated by between one and three people.  Many of the variables estimated are strongly correlated with one another.

While likely of interest to the readers of Forests, this manuscript has several serious drawbacks.  First, there is no replication (only one sawmill, only one to three operators).  Thus, this is really a case-study.  I don’t believe this precludes publication, but this needs to be written throughout as a case study and not as an experiment or experimental design.  This will also need to be addressed with whatever statistical methods are employed.

Second, the entire paper needs significant revisions for English language and grammar.  Incorrect words are used in some cases.  While technically correct, I don’t think promiscuous is the best word choice to describe the Italian sawmills’ work environment (line 111).

Third, the authors spend too much time discussing sawmilling in general or in an abstract way, and too little time clarifying the importance of this work, and how all the disparate variables (productivity, posture, noise) are linked.  Clearly defined hypotheses, if there were any, could help bring better focus to the intro, results, and discussion sections.

Abstract:

The abstract contains too much introduction and none of the results.  Rebalance it.

Response: We would like to thank you for your comment. The abstract was integrated with results and rebalanced.

 

Keywords:         

Overly generic (mechanization, efficiency, sustainability)

Response: We would like to thank you for your suggestion. We have inserted yield; lumber production and safety respect to mechanization, efficiency, sustainability.

 

Introduction:

First half of first paragraph is overly generic intro.  Omit.

Line 50 – if inefficient sawmilling is no longer sustainable, then how do small sawmills, which are inherently inefficient, fit it?

Response: We have partially omitted the first part of introduction and several sentences not correctly explained. Thank you for your suggestion.

 

Could streamline the justification for studying small sawmills in lines 69-85.

Response: We have partially reduced this part. Thank you for your comment

 

Line 114 – why simply summarize methods of a study rather than results?  How were their results relevant to this study?

Response: We would like to thank you for your suggestion. We have integrated their results.

 

Line 123: Common sense line seems a bit pedantic.  Recommend rephrasing.

Response: Thank you for your suggestion. The text has been improved.

 

Overall the introduction covers relevant literature, but doesn’t highlight what was observed in those studies, or how that lead the authors to their research objective.  Intro needs considerable work.

Response: text has been improved in the last paragraph of the introduction to better reflect what the study was about. Indeed, the performance of sawmills depends on many factors such as the type of equipment used, scale and the variability of inputs. We have improved this part of our introduction and the updated text is given in red.

 

Were there any hypotheses that were tested?

Response: we have added the hypotheses in the last paragraph of the introduction section.

 

Methods:

Line 138: need scientific names for these two trees.

Response: added into the text.

 

So this study is of a single sawmill with only 3 workers?  This basically means that none of the data are replicated.  Collecting multiple days’ worth of data is a form of pseudoreplication.  This study needs to be more clearly described as a case study, which is what it is.  There is no experiment, or experimental design, as there is no true replication.  This should be reflected clearly in the title, abstract, methods, and results sections.  Logs are not the level of replication.  Either the sawmill or maybe the workers are.

Response: thank you for this comment. The text has been updated accordingly.

 

TMD should be included in table 1

Response: included in the table.

 

Line 203: It is unclear if they only used 6 days of noise data, or if they somehow extrapolated the six days of data to predict noise levels for day 7.  Clarify and if the latter more details are required.

Response: clarified in the text.

 

Line 214: The postural analysis seems pretty unreliable given that only up to 3 people were observed.  Height of this specific equipment and these specific operators seems like it might heavily influence the results.  The lack of replication makes the broader applicability of these observations pretty dubious.

Response: we acknowledge the concerns of the reviewer, and we are aware that the results apply only to this type of equipment. On the other hand, it is rather difficult to find a large enough pool of small companies willing to participate in studies such as ours, therefore, in our opinion, the data presented on the postural analysis is better than nothing. One needs also to think about the particularly low production rates/outputs, which makes long or distributed data collection unfeasible. Manually driven bandsaws have some principles of ergonomics embodied into them in terms of working height, although it may be reflected only by the experience of practice. Of course, anthropometry plays an important role in biomechanical exposure and we are aware of its effects on the working postures. However, according to the method used, much of the results account for qualitative changes in the particular body segments, without actually giving the exact deviations (i.e. angles or distances) from a neutral posture. In our opinion, this is one of the benefiting features of the method used which is purely observational.

 

Line 238: Why does unreplicated data need to be normally distributed?  I’m assuming they simply entered all these data points from different logs or different days, and treated those as different samples.  They are not, since this isn’t an experiment, but rather a case study.  This criticism applies to all the statistical methods described in this paragraph.

Response: checking for normality in a sample is a typical step in statistical analysis, because on its results one may choose the best approach to describe and/or model the data. There are dozens of statistical textbooks as well as good practice guidelines explaining the importance of such tests in statistical analysis. If needed, we can provide to the reviewer some of these. Indeed, the data collected in the days of observation were treated as a sample. In our knowledge, a sample is made of a set (number) of statistical observations. We believe that the data given in Table 2 supports this as we have given there the sample size (N). At least the observational modelling studies dealing with the evaluation of productivity and time consumption make use of samples that include observations framed around work elements and/work cycles, an approach that has been used in our study.

 

Line 268: Need more details than ‘the usual formulae and approaches were used’.

Response: we acknowledge the concern of the reviewer on this part of the manuscript. However, the referred methods were already described in the mentioned sources and we believe that their description here would be redundant according to the instructions for authors.

 

How many operators were these data collected from?  If more than one operator, were differences observed between the operators?  This seems relevant.

Response: as described in the materials and methods (lines 141-142) a single worker operates the machine, therefore the data applies to him.

 

Results:

People who are red-green colorblind will not be able to discern P from R in figure 2.  Use different shapes in addition to different colors.

Response: thank you for this comment. We acknowledge this problem and we have changed the figures accordingly.

 

The authors routinely use the word ‘statistics’ to describe data.  Clarify.

Response: we suppose that the reviewer refers to the section 3.1 of the results. Also, we feel that clarification on this term is rather redundant in the text, if by the above comment, the reviewer refers to such a clarification. Please check, for instance: https://en.wikipedia.org/wiki/Descriptive_statistics.

 

The presented postural codes (1 – 7) are never described or defined.  This needs to be done somewhere so the data may be interpreted.

Response: thank you for this comment. For the same reason as previously mentioned, and according to the instructions for the authors given in the paper template, we have chosen not to duplicate the information on methods used since it is clearly described elsewhere. Lines 213-220 make clear references to the method used and the meaning of the concepts and codes. However, for a better clarity, we have further commented our results on the postural analysis by including a description where appropriate. The changes are given in red.

 

Discussion:

The authors state that analyzing efficiency and safety together are common sense, yet they present these data separately and never really draw any linkages between them.  How are productivity and safety related based on these data?

Response: thank you for this comment. We have included additional text in the discussion section to discuss the studied performance areas together.

 

The discussion seems pretty superficial. They do provide context with the literature, but it is unclear what the interpretation of these data is. How are productivity and safety linked? How might improving productivity alter safety?  What factors (e.g. log size) most influenced the variables measured related to safety?  Did log volume being milled impact noise?  There seem to be a lot of analyses and discussion left on the table that could better tie the manuscript together.

Response: thank you for this comment. We have done our best to improve the discussion so as to account for the interrelations between productivity and safety. All the changes are given in red.

 

Ancillary:

Should the fact that a co-author owns this sawmill be included in the Conflicts of Interest statement? 

The authors felt the need (understandably so) to disclose this in the methods section.

 

Response: thank you for this comment. We believe that the inclusion of a supplementary statement in the conflicts of interest is not necessary. This is because the data analysis was distributed among the authors of the paper, therefore the possible influence of the company owner on the study results was removed/limited, though he is one of the authors.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

In my opinion the authors didn't adequately address my primary concerns (statistical methods, this is really just a case study).  I also believe this manuscript needs a more thorough review by a subject matter expert in a more closely aligned field.  It is definitely of interest to the readers of Forests, but requires more peer review and revision.