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: 01 Apr 2019  
Reviewer: Abiodun Adewuya  
Reviewer's report:  
This is an important and timely research as measurement of loneliness is increasingly becoming 
important especially in mothers caring for infants and toddlers.  
It is a well written paper, well justified, appropriate methods and analysis and the discussion is 
well focused .  
 
Just some fe w points  
1. In line 155 -156, the desired sample size was set as a quarter of 2000 which is 500, at the 
end only 430 were sent questionnaire and only 248 replied. This is less than 50% of the 
desired sample size. I expect the authors to have either improvi sed by sending more 
questionnaires out before analysis. As this was not done, it should have been mentioned 
as a limitation of the study.  
2. The analysis for the SF -10 and SF -3 were based on the completed UCLA -LS3-J which is 
a 20-item questionnaire. An in creasingly important observation is that responses to a set 
of questions may be affected or biased by the presence of previous questions on the same 
scale. It would have been nice to know if the answer to the 3 questions of the SF -3 would 
have been the sam e were the other 17 questions of UCLA -LS3-J not present in the 
questionnaire. This is important as the study did not evaluate for test -retest reliability or 
discriminant validity.  
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.  
 
Unable to assess  
 
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 am able to assess the statistics  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Acceptable  
 
Declaration of competing interes ts 
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