Review Reports - Willingness to Pay for Improved Household Solid Waste Collection in Blantyre, Malawi

Round 1

Reviewer 1 Report

It is an interesting manuscript. It is a relevant research topic that has been investigated, and with a relevant research method. However, the manuscript has some lacks and needs to be developed before publishing.

The introduction is a little poor.

After the lines 25 – 28 you should add an explanation that the implementation of waste management requires financing and financing by private people by fees is one possibility, and it is important to know how much people is willing to pay (or something similar).

You should also have a better geographic introduction, mentioning that Blantyre is the second city in Malawi. Also mention the area South Lunzu in this connection.

Also, the population really 18,091,580 people in 2016? Wikipedia (which often is a bad reference!) mentions 1,068,681 inhabitants as of 2015?

After that you can have an introduction about the method (just like you have in lines 37 – 59).

You should also have a more clear description of the state-of-the-art. Now yoy just read “without waste collection services”, but that should be developed. How the waste is managed, what problems have been identified and so on.

To make it easier to understand the result, you should somewhere explain the currency K and give the exchange rate to for example Euro or USD.

Table 4 is very difficult to read. You should split up the table to several tables.

The first conclusion should be more modest worded (line 295). You can also see interpret the result that 44% are not willing to pay, and 44% is a large share of the population.

It would be valuable if you can add a discussion about the current waste management in the Discussion or Conclusion. In the questionnaire you ask about how people dump there wastes today and if they are satisfied with the disposal today. Is there any correlation between the WTP and the current waste management or how satisfied people are with the current management?

The references should be edited. There are references missing, for example (National Statistical Office, 2008), and in the reference list (last page in the manuscript) the references should be presented in alphabetical order.

Author Response

We appreciate the detailed comments from the reviewer and have replied in italics below (please note that due to significant editing, the line references by the reviewer are no longer valid, but our replies reflect the changes' new location).

The introduction is a little poor.

+The introduction has been reworked

+This has been addressed on line 48

You should also have a better geographic introduction, mentioning that Blantyre is the second city in Malawi. Also mention the area South Lunzu in this connection.

+The paragraphs have been rearranged and the more information has been included

Also, the population really 18,091,580 people in 2016? Wikipedia (which often is a bad reference!) mentions 1,068,681 inhabitants as of 2015?

+The last census was conducted in 2006 and so we have included the most recent, citable source (661,256)

After that you can have an introduction about the method (just like you have in lines 37 – 59).

+This has been addressed starting on line 59

+This has been addressed on lines 31 and 46 (including reference to Palamuleni et al 2002)

To make it easier to understand the result, you should somewhere explain the currency K and give the exchange rate to for example Euro or USD.

+A USD conversion is provided on line 121

Table 4 is very difficult to read. You should split up the table to several tables.

+Unfortunately, without losing the ability to make direct variable-wise comparisons there is not a better way to present the data; we are hopeful that once the manuscript is formatted for the journal, it will be easier to read.

The first conclusion should be more modest worded (line 295). You can also see interpret the result that 44% are not willing to pay, and 44% is a large share of the population.

+The context of this statement is more fully explained on line 316

+We found no correlation between the present practices and the WTP and this has been added to line 334.

+This has been corrected

Reviewer 2 Report

Author should discuss more in detail differences between the stated preferences and the revealed preferences, ideally find some studies where these two approaches were compared. And according to this comment on the acquired results.

Author could also comment more on the different WTP depending on the framing of the question and thus the possibility of influencing the public opinion towards both higher or lower WTP, depending on the overall objective. The aspect of anchoring in the questions could be also discussed with respect to the „nudge“ concept.

It is not clearly defined in the beginning of the study to what period is the estimated price for the service related (a month, year,…).

Around line 102 author could provide Exchange rate using purchase power parity or the percentage of the asked bid from the typical income in the area in order to get better idea about the relative costs of the waste collection from the perspective of the local people. This would be useful also for international comparison.

Author could define scenario 1 more precisely around the line 116 – kerbside collection typically means that the containers are placed directly outside the house, thus the distance from the household is practically none. Author could also further discuss the improved convenience of the waste collection for the people with the existing literature, if the necessary distance to cover with the waste is decreased – people save time, thus are willing to pay more for such more convenient solution.

There might be a potential error in the table 3 in the values of household income for the final study sample.

Table 3 suggests that the current time taken to travel to and from waste disposal site is under 7 minutes. Compared to the 30 minutes in scenario 2, this seems as a much worse option for the people compared to the current state – author should clarify this. Also in the table 3 the estimated travel time is for travel to and from the disposal site – this should be also more precisely addressed in the scenarios, whether the estimated time is for round trip. Moreover, it should be also clarified whether the fees in scenarios are calculated per person or per household or per what unit (same applies to the generated solid waste quantity).

Variable used in the model in table 4 should be described more precisely, what were the available values for the variables, what actually do they represent, etc. Appendix B is insufficient in this regard.

Results on lines 207-8 seem inconsistent – one time scenario 1 is more valued, the other time scenario 2 is.

Results in table 4 should be interpreted rather as a suggested trend caused by the variables and not taken literally.

Results should contain only results and further explanations of the potential reasons for the acquired values – this should be included in the discussion section. Ideally the results section should be clear enough in order not to require additional explanation, and if just basic comments. The rest should be in the discussion.

Line 224 key differences were…

Interesting observation is that people were willing to pay less if the valuation question was placed before – often people are willing to pay more once the topic is introduced to them more in detail, but this also depends on the specific way how such question would be given and thus could potentially affect WTP both ways.

Table 5 contains same base WTP results for both scenarios. And also in some additional cases it seems inconsistent that people would be willing to pay more for 30 min walk scenario compared to 5 min walk scenario. I suggest the values in table 5 to be carefully double-checked.

The discussion should include also estimated comparison of costs for both scenarios, whether the estimated aggregated WTP has the real potential for financing such solution. This should be among the main goals. One of the main reason for using WTP is to monetize non-market goods or services in the CBA with the final result being the answer whether the project makes economic sense (benefits outweigh the costs). Therefore one of the results of this study should be also the answer whether total potential WTP is able to finance proposed waste collection scenarios. This is included only at the very end in conclusions, but should appear in discussion and be much more commented on.

Remark concerning higher WTP of women on line 285 might be also result of usual situation when women stay much more at the household and thus have to deal with the household waste more often, while men often spend much more time at work outside of the house and thus are not that much exposed to the household waste issue. So far, rather limited amount of literature is dealing with this aspect.

Multiple parts of conclusions, especially those discussing the results with the available literature, should be in the discussion part. The conclusions section should only contain conclusions and very little (if at all) additional comments.

Author Response

We appreciate the thoughtful and helpful comments provided by the reviewer and have replied in bullet points below: Author should discuss more in detail differences between the stated preferences and the revealed preferences, ideally find some studies where these two approaches were compared. And according to this comment on the acquired results. +We have discussed this section further starting on line 51 Author could also comment more on the different WTP depending on the framing of the question and thus the possibility of influencing the public opinion towards both higher or lower WTP, depending on the overall objective. The aspect of anchoring in the questions could be also discussed with respect to the „nudge“ concept. +This has been more fully clarified starting on line 141 It is not clearly defined in the beginning of the study to what period is the estimated price for the service related (a month, year,…). +In Table 2 we clarify that the payment is made by the household, on a monthly basis to a to a community managed account Around line 102 author could provide Exchange rate using purchase power parity or the percentage of the asked bid from the typical income in the area in order to get better idea about the relative costs of the waste collection from the perspective of the local people. This would be useful also for international comparison. +we have added the GDP per person ($PPP) to help better contextualize the values on line 121. Author could define scenario 1 more precisely around the line 116 – kerbside collection typically means that the containers are placed directly outside the house, thus the distance from the household is practically none. Author could also further discuss the improved convenience of the waste collection for the people with the existing literature, if the necessary distance to cover with the waste is decreased – people save time, thus are willing to pay more for such more convenient solution. +We have clarified that “kerbside” also implies “roadside” only in this case, there are no actual “kerbs” on which to place the trash. There might be a potential error in the table 3 in the values of household income for the final study sample. +the value is correct, but the comma was in the wrong place: it is 111,512 Mk or approximately $150/month Table 3 suggests that the current time taken to travel to and from waste disposal site is under 7 minutes. Compared to the 30 minutes in scenario 2, this seems as a much worse option for the people compared to the current state – author should clarify this. +This is a correct observation and some respondents were willing to participate despite disposing of their wastes in a pit behind the household. Thus the longer time tested how far people were willing to go to attain proper disposal. We have added text on line 285. Also in the table 3 the estimated travel time is for travel to and from the disposal site – this should be also more precisely addressed in the scenarios, whether the estimated time is for round trip. Moreover, it should be also clarified whether the fees in scenarios are calculated per person or per household or per what unit (same applies to the generated solid waste quantity). +In both cases, it was the distance to the disposal site that was estimated, not to and from. Table 2 has been amended to reflect the times and the fact that the fees are calculated per household Variable used in the model in table 4 should be described more precisely, what were the available values for the variables, what actually do they represent, etc. Appendix B is insufficient in this regard. +The units and coding for the variables are now included on line 224 Results on lines 207-8 seem inconsistent – one time scenario 1 is more valued, the other time scenario 2 is. +Correct, and this is a result of the question framing and the covariates Results in table 4 should be interpreted rather as a suggested trend caused by the variables and not taken literally. +Of course economic models should never be taken literally! It is simply a first attempt to disaggregate the profile of someone who may or may not pay for SWM Results should contain only results and further explanations of the potential reasons for the acquired values – this should be included in the discussion section. Ideally the results section should be clear enough in order not to require additional explanation, and if just basic comments. The rest should be in the discussion. +we have reorganized some of the text in this way Line 224 key differences were… +We’re not sure what you mean with this statement Interesting observation is that people were willing to pay less if the valuation question was placed before – often people are willing to pay more once the topic is introduced to them more in detail, but this also depends on the specific way how such question would be given and thus could potentially affect WTP both ways. +In Table 5 you can see that the WTP for either scenario is lower when the WTP question comes before the environmental framing question (i.e. position 1 is lower than position 2), as would be expected. The difference is not always significant (e.g. educated vs. non-educated) but the direction is consistent. Table 5 contains same base WTP results for both scenarios. And also in some additional cases it seems inconsistent that people would be willing to pay more for 30 min walk scenario compared to 5 min walk scenario. I suggest the values in table 5 to be carefully double-checked. +It is an important point that you raise: the values are reversed for one set of responses: the comparison between educated and non-educated respondents. In fact, it highlights the challenges of comprehension with this type of method for some segments of the population. Though it is a fairly straightforward method, it does require some hypothesizing and thinking into the future, which is not always easy for those not used to thinking in the abstract. The discussion should include also estimated comparison of costs for both scenarios, whether the estimated aggregated WTP has the real potential for financing such solution. This should be among the main goals. One of the main reason for using WTP is to monetize non-market goods or services in the CBA with the final result being the answer whether the project makes economic sense (benefits outweigh the costs). Therefore one of the results of this study should be also the answer whether total potential WTP is able to finance proposed waste collection scenarios. This is included only at the very end in conclusions, but should appear in discussion and be much more commented on. +Starting on line 368, we state the maximum amount that could be collected if the stated values were true. Certainly, a real scheme would never achieve such a theoretical value, but our goal was to indicate, more broadly, the willingness to give a) something and then b) estimate how much that could be. Realistically, even if only 10% of the estimated total were to be collected (i.e. 2 million kwacha/month) a huge improvement in waste management (through the hiring of dedicated workers, paying for petrol, installing collection points, etc.) could be realized. We therefore hesitate to speculate on what could or could not be implemented without attempting to validate the stated preferences. We are hopeful that this work will attract further funding such that we could pilot the proposed systems and in turn, determine, what the actual WTP is and what kind of SWM system could be developed with the funds generated. Remark concerning higher WTP of women on line 285 might be also result of usual situation when women stay much more at the household and thus have to deal with the household waste more often, while men often spend much more time at work outside of the house and thus are not that much exposed to the household waste issue. So far, rather limited amount of literature is dealing with this aspect. +Good point. Another variable that could have been included would have been time spent by the respondent at home. This might have affected the WTP but unfortunately we did not include it and we can not retrospectively hypothesize about how much time the respondent spends at home (indeed women in Malawi spend a great deal of time farming). Multiple parts of conclusions, especially those discussing the results with the available literature, should be in the discussion part. The conclusions section should only contain conclusions and very little (if at all) additional comments. +We have removed the two citations in the conclusions

Reviewer 3 Report

Although I recommend acceptance of this work, I do suggest that a proper editorial and grammatical review of the article be made before publication.

For example line 8 "Additionally, we tested the impact of the question positioning relative to environmental perceptions on respondents’ WTP", the question was not stated prior to this statement and also it should be "perceptions of respondents" not "perception on respondents

Lines 13 and 14, should be "on the environment"

Repetition in line 225 and line 227 about odd and even numbered columns and what they represented.

The is a mention of table 7 in 276 but no such table found

Also, Lines 45 to 73 could be part of the discussion to affirm your chosen methodology and support the analysis of your results

Author Response

We thank the reviewer for these helpful comments! Our replies are in bold below:

We have modified the sentence to clarify that the question is the WTP question, but in fact, we are testing the impact of positioning ON the WTP, so have left this as is: “Additionally, we tested the impact of the WTP question positioning relative to environmental perceptions on respondents’ WTP”

Lines 13 and 14, should be "on the environment"

corrected

Repetition in line 225 and line 227 about odd and even numbered columns and what they represented.

corrected

The is a mention of table 7 in 276 but no such table found

Corrected (it was supposed to be Table 3)

Also, Lines 45 to 73 could be part of the discussion to affirm your chosen methodology and support the analysis of your results

Absolutely, but a different reviewer ask that this sentence be added here to introduce the concept of independent contracting and for that reason, we have opted to leave it here, and re-emphasize the notion on line 107