Reviewer ’s report  
 
Title: Reliability and validity of Japanese versions of the UCLA Loneliness Scale Version 3 for 
use among mothers with infants and toddlers: A cross -sectional study  
 
Version: 0 Date: 19 Apr 2019  
 
Reviewer: Marta Rondon  
Reviewer's report:  
Please describe what "loneliness" means as opposed to isolated. The way it is presented in lines 
95 to 97 of the introduction is tautological. And it probab ly should appear at the beginning of the 
introduction.  
Methods: please define affluent, etc in the sociodemographic data. Is this based on a 
conventional Japanese classification? How did you decide to which category a person belongs?  
The exclusion criteria  are not mentioned. For instance, would a women undergoing treatment for 
postpartum depression be included? How would this affect the results?  
Results: I am impressed by the low response rate. Would this be attributable to the fact that 
women had to mail i n the responses?  
Discussion: I find it a bit rambling. Loneliness is not related to self perceived quality of health, 
or size of the social network but rather to some ill defined quality factor in  interactions. Also, it 
seems to be related to regional fac tors, which I understand is how mothers interact with 
neighbors.  
So wouldn´t relationships with neighbors be part of the informal support system?  
I'd suggest that the discussion concern itself only with the psychometric qualities of the 
Loneliness Scale.  
Are the methods appropriate and well descri bed?  
If not, please specify what is required in your comments to the authors.  
 
Yes 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Yes 
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
Yes 
 
Are you able to assess any statistics in the manuscript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommended, please specify what aspects require further 
assessment in your comments to the editors.  
 
I recommend additional statistical review  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Acceptable  
 
Declaration of competing interes ts 
Please complete a declaration of competing interests, considering the following questions:  
 
1. Have you in the past five years received reimbursements, fees, funding, or salary from an 
organisation that may in any way gain or lose financially from the publ ication of this 
manuscript, either now or in the future?  
 
2. Do you hold any stocks or shares in an organisation that may in any way gain or lose 
financially from the publication of this manuscript, either now or in the future?  
 
3. Do you hold or are you current ly applying for any patents relating to the content of the 
manuscript?  
 
4. Have you received reimbursements, fees, funding, or salary from an organization that 
holds or has applied for patents relating to the content of the manuscript?  
 
5. Do you have any other financial competing interests?  
 
6. Do you have any non -financial competing interests in relation to this paper?  
 
If you can answer no to all of the above, write 'I declare that I have no competing interests' 
below. If your reply is yes to any, please give det ails below.  
 
I declare that I have no competing interests.  
 
I agree to the open peer review policy of the journal. I understand that my name will be included 
on my report to the authors and, if the manuscript is accepted for publication, my named report 
including any attachments I upload will be posted on the website along with the authors' 
responses. I agree for my report to be made available under an Open Access Creative Commons 
CC-BY license ( http://creativecommons.org/licenses/by/4.0/ ).  I understand that any comments 
which I do not wish to be included in my named report can be included as confidential comments 
to the editors, which will not be published.  
 
I agree to the open peer review policy of the journal