PONE-D-21-22179Estimation of Cost Efficiency of fattening pigs, sows, and piglets using SFA approach analysis: evidence from ChinaPLOS ONE

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Additional Editor Comments:

Dear authors, in order to improve the quality of your manuscript, I suggest making the improvements indicated by the reviewers, in the same way I ask you to consider the suggested references.

References

share some literature that you can use to reinforce some aspects of the DEA approach and its use with the Tobbit model:

1) González, C. A. Z. (2011). Technical efficiency of organic fertilizer in small farms of Nicaragua: 1998-2005. African Journal of Business Management, 5(3), 967-973. Available from publons.com/p/11272633/

2) Dios-Palomares, R. (2015). 7. Analysis of the Efficiency of Farming Systems in Latin America and the Caribbean Considering Environmental Issues. Revista Cientifica-Facultad de Ciencias Veterinarias, 25(1). Available in publons.com/p/3106827/

3) Zuniga González, C. (2020). Total factor productivity growth in agriculture: Malmquist index analysis of 14 countries, 1979-2008 . REICE: Revista Electrónica De Investigación En Ciencias Económicas, 8(16), 68-97. https://doi.org/10.5377/reice.v8i16.10661 Available from publons.com/p/36247914/

4) Blanco-Orozco, N., Arce-Díaz, E., & Zúñiga-Gonzáles, C. (2015). Integral assessment (financial, economic, social, environmental and productivity) of using bagasse and fossil fuels in power generation in Nicaragua. Revista Tecnología en Marcha, 28(4), 94-107. Available from publons.com/p/32281799/

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: No

Reviewer #2: Partly

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: No

Reviewer #2: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available?

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Reviewer #1: No

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

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Reviewer #1: No

Reviewer #2: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The article under review aims at measuring cost efficiency of three different pig farming systems in China covering the period 2008-2018 and analyse the influence of environmental regulation policies in explaining the calculated cost efficiency.

Overall, the paper suffers from a major methodological flaw that precludes its publication in its current form. The present paper uses a two-stage equations to (1) estimate the cost-efficiency through SFA and (2) to analyse the efficiency determinants. This approach is considered to be not the appropriate method in the SFA framework as the error terms of the two equations could be correlated.

I suggest using one of the following approaches:

• One stage estimation through SFA: The determinants of the inefficiency should be explicitly introduced in model. See (Coelli & Battese, 1996; Kumbhakar et al., 1991; Tzouvelekas et al., 2001)

• Two-stage estimation through DEA: you can follow the same approach as your original analysis, with the estimation of DEA efficiency scores and then you perform a Tobit model to analyse the effects of contextual variables. It is worth mentioning that a censored Tobit model might be inappropriate because of serial correlation, therefore, you could apply a more robust estimation method such as the one proposed by Simar & Wilson (2007).

References

Coelli, T., & Battese, G. (1996). Identification of factors which influence the technical inefficiency of Indian farmers. Australian Journal of Agricultural and Resource Economics, 40(2), 103–128. https://doi.org/10.1111/j.1467-8489.1996.tb00558.x

Kumbhakar, S. C., Ghosh, S., & McGuckin, J. T. (1991). A Generalized Production Frontier Approach for Estimating Determinants of Inefficiency in U.S. Dairy Farms. Journal of Business & Economic Statistics, 9(3), 279. https://doi.org/10.2307/1391292

Simar, L., & Wilson, P. W. (2007). Estimation and inference in two-stage, semi-parametric models of production processes. Journal of Econometrics, 136(1), 31–64. https://doi.org/10.1016/j.jeconom.2005.07.009

Tzouvelekas, V., Pantzios, C. J., & Fotopoulos, C. (2001). Technical efficiency of alternative farming systems: The case of Greek organic and conventional olive-growing farms. Food Policy, 26(6), 549–569. https://doi.org/10.1016/S0306-9192(01)00007-0

Reviewer #2: Review of the manuscript PONE-D-21-22179 by Gangyi Wang et al.

The manuscript describes retrospective analysis of data originating from official data sources like National Compendium of Agricultural Product Cost-benefit Data, China Statistical Yearbook, China Statistical Yearbook of Science and Technology, and Brick agricultural data terminals. The Authors have chosen 23 provinces representing intensive swine farming area. The data from decade (2008-2018) were analyzed using two standard models to receive information about cost efficiency in macroeconomic scale.

The manuscript seem to be interesting. The analysis is of practical importance, including potential to use models for prediction of cost and production efficiency after relevant changes of production environment, especially administrative burdens. That is why in my opinion the manuscript meets the requirements of PLOS One in terms of the scope of the Journal. However, some amendments are needed before acceptance.

Introduction is well written and characterize clearly the practical importance of research. However, there is no clearly defined aim of the study at the end of Introduction. The last paragraph seem to be more M&M summary, so the aim of the study is defined only as one general sentence at the beginning of Abstract. It is not enough, and clear definition of the aim of the study must be add. Additionally I would suggest to add information about more international currency (e.g. USD), because the value of yuan is difficult to interpret for international reader.

M&M

The study is based on retrospective analysis of macroscale data, that is why the most important is to define clearly variables to analyze and models. The models are defined, however variables only generally in the text, and a little more detailed in table 3. This table must be corrected, because variables in table poorly correspond to the text of M&M, and thus the table is difficult to interpret. First of all, variables in the table should be named to be interpretable reading only table (without text). And second, variables should be characterized also with units (is this only cost in currency, or the other units were used). In my opinion, it would be also interesting to know production parameters to compare them with costs. The Authors base on statistical year books, so I am pretty sure, that such data is also possible to obtain. It is important because e.g. feed intake and FCR influence costs of production significantly.

Results are described very detailed, and after corrections in M&M should be OK.

Discussion is very general and seem to be more reediting of results than critical interpretation. The specificity of data analysis suggests, that maybe it would be better to compose manuscript without separate discussion, and change it to Results and discussion as one section. Anyway, this section should and with conclusion. There is no such separate section, and the manuscript seem to have no clear end, and no suggestion for practice. This must be corrected and completed.

To summarize, in my opinion the manuscript could be interesting, but must be improved. Minor language revision is also required.

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Reviewer #1: No

Reviewer #2: No

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Estimation of cost efficiency of fattening pigs, sows, and piglets using SFA approach analysis: evidence from China

PONE-D-21-22179R1

Dear Dr. chang'e zhao,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Kind regards,

Carlos Alberto Zúniga-González, Ph.D

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Dear authors, I sincerely congratulate you for the effort made to improve the manuscript, I see that you have made a good effort and followed the authors' suggestions, although I do not see the suggested references incorporated.

Reviewers' comments: