Hi,
I have performed an insomnia prevalence study among academics using ISI. I have come across the floor and ceiling effect in a cross-sectional survey. I want to estimate the same percentage of each ISI question and the total score. It would be helpful to see an example to calculate the same.
I would appreciate your help in enhancing my knowledge.
Hi,
Look at the distribution of scores whether they are skewed. Correct for the skew by some transformation and again look for the distribution. You may be able to do further analysis. Conversely, frequencies in the categories can be compared.
Here are a few references on the Psychometric properties and its use in some studies of the scale:
Morin CM, Belleville G, Bélanger L, Ivers H. The Insomnia Severity Index: psychometric indicators to detect insomnia cases and evaluate treatment response. Sleep. 2011 May 1;34(5):601-8. doi: 10.1093/sleep/34.5.601
https://www.thoracic.org/members/assemblies/assemblies/srn/questionaires/isi.php
Schulte, T., Hofmeister, D., Mehnert-Theuerkauf, A. et al. Assessment of sleep problems with the Insomnia Severity Index (ISI) and the sleep item of the Patient Health Questionnaire (PHQ-9) in cancer patients. Support Care Cancer 29, 7377–7384 (2021). https://doi.org/10.1007/s00520-021-06282-x
Yusufov M, Zhou ES, Recklitis CJ. Psychometric properties of the Insomnia Severity Index in cancer survivors. Psychooncology. 2019 Mar;28(3):540-546. doi: 10.1002/pon.4973
Ohayon MM. Epidemiology of insomnia: what we know and what we still need to learn. Sleep Med Rev. 2002 Apr;6(2):97-111. doi: 10.1053/smrv.2002.0186
Okajima I, Miyamoto T, Ubara A, Omichi C, Matsuda A, Sumi Y, Matsuo M, Ito K, Kadotani H. Evaluation of Severity Levels of the Athens Insomnia Scale Based on the Criterion of Insomnia Severity Index. Int J Environ Res Public Health. 2020 Nov 26;17(23):8789. doi: 10.3390/ijerph17238789
Gagnon C, Bélanger L, Ivers H, Morin CM. Validation of the Insomnia Severity Index in primary care. J Am Board Fam Med. 2013 Nov-Dec;26(6):701-10. doi: 10.3122/jabfm.2013.06.130064
Kraepelien M, Blom K, Forsell E, Hentati Isacsson N, Bjurner P, Morin CM, Jernelöv S, Kaldo V. A very brief self-report scale for measuring insomnia severity using two items from the Insomnia Severity Index - development and validation in a clinical population. Sleep Med. 2021 May;81:365-374. doi: 10.1016/j.sleep.2021.03.003
have you used the MeSH browser in PUBmed to do a search with search terms to see what is in the literature?
Vidusha Karavadi Hakan Lane, check the useful refernces. I believe these would be helpful for you as well.
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