Saturation of data has been acknowledged by many social scientists as evidence of rigor in qualitative research. Though there is a consensus about its definition and usefulness in qualitative research, the methods for achieving saturation are scarce while the social scientists who mention data saturation in their research methodologies do not adequately describe how this is achieved. This paper describes a new method for achieving saturation in studies that use interviews. The method is called Comparative Method for Themes Saturation (CoMeTS). CoMeTS is comparative in two ways. First, all themes from all interviews are compared with each other. Second, the sequence of interviews is reordered multiple times in order to check saturation again. This is because the sequence of interviews during the check makes saturation vary and, therefore, reordering helps confirming saturation. This paper concludes that CoMeTS is a simple, comparative and holistic method for achieving saturation and that it can be used in complicated qualitative studies.
AndoHCousinsRYoungC (2014) Achieving saturation in thematic analysis: development and refinement of a codebook. Comprehensive Psychology3(4): 1–7.
2.
BakerSEEdwardsR (2012) How many interviews is enough? National Centre for Research Methods, Economic and Social Research Council (ESRC).
3.
BertauxD (1981) From the life history approach to the transformation of sociological practice. In: BertauxD (ed.) Biography and Society: The Life History Approach in the Social Sciences. London: SAGE, 29–45.
4.
BowenGA (2008) Naturalistic inquiry and the saturation concept: a research note. Qualitative Research8(1): 137–152.
5.
BowlingA (2014) Research Methods in Health: Investigating Health and Health Services (fourth edition). London: McGraw-Hill.
6.
BrymanA (2012) Social Research Methods (fourth edition). Oxford: Oxford University Press.
7.
CreswellJ (1998) Qualitative Inquiry and Research Design: Choosing Among Five Traditions. Thousand Oaks, CA: SAGE.
8.
FrancisJJJohnstonMRobertsonCGlidewellLEntwistleVEcclesMPGrimshawJm (2010) What is an adequate sample size? Operationalising data saturation for theory-based interview studies. Psychology and Health25(10): 1229–1245.
9.
FischerEHFarinaA (1995) Attitudes toward seeking professional psychological help: a shortened form and considerations for research. Journal of College Student Development36(4): 368–373.
10.
FontanellaBJBLuchesiBMSaidelMGBRicasJTuratoERMeloDG (2011) Sampling in qualitative research: a proposal for procedures to detect theoretical saturation. Cadernos de Saúde Pública27(2): 388–394.
11.
FugardAJPottsHW (2015) Supporting thinking on sample sizes for thematic analyses: a quantitative tool. International Journal of Social Research Methodology, 18(6): 669–684.
12.
FuschPINessLR (2015) Are we there yet? Data saturation in qualitative research. The Qualitative Report20(9): 1408–1416.
13.
GersonKHorowitzR (2002) Observation and interviewing: options and choices. In: MayT (ed) Qualitative Research in Action. London: SAGE, 199–224.
14.
GlaserBStraussA (1967) The Discovery of Grounded Theory: Strategies for Qualitative Research. New York: Aldine Publishing Company.
15.
GubaEG (1981) Criteria for assessing the trustworthiness of naturalistic inquiries. Education Communication and Technology29(2): 75–91.
16.
GuestGBunceAJohnsonL (2006) How many interviews are enough? An experiment with data saturation and variability. Field Methods18(1): 59–82.
17.
HillCESatterwhiteDBLarrimoreMLMannARJohnsonVCSimonRESimpsonACKnoxS (2012) Attitudes about psychotherapy: a qualitative study of introductory psychology students who have never been in psychotherapy and the influence of attachment style. Counselling and Psychotherapy Research12(1): 13–24.
18.
MarshallBCardonPPoddarAPontenotR (2013) Does sample size matter in qualitative research? A review of the literature in IS research. Journal of Computer Information Systems11–22.
19.
MasonM (2010) Sample size and saturation in PhD studies using qualitative interviews. Forum: Qualitative Social Research11(3): Art.8.
20.
MorseJ (1995) The significance of saturation. Qualitative Health Research5(2): 147–149.
21.
MorseJ (2015) ‘Data were saturated…’ Qualitative Health Research25(5): 587–588.
22.
OnwuegbuzieAjCollinsKMT (2007a) A typology of mixed methods sampling designs in social science research. The Qualitative Report12(2), 281–316.
23.
OnwuegbuzieAJLeechNL (2007b) A call for qualitative analyses. Quality & Quantity41: 105–121.
24.
O’ReillyMKiyimbaN (2015) Advanced qualitative research: a guide to using theory. London: SAGE.
25.
O’ReillyMParkerN (2012) ‘Unsatisfactory saturation’: a critical exploration of the notion of saturated sample sizes in qualitative research. Qualitative Research13(2): 190–197.
26.
OrmstonRSpencerLBarnardMSnapeD (2014) The foundations of qualitative research. In: RitchieJLewisJNichollsCMOrmstonR (eds) Qualitative Research Practice: A Guide for Social Science Students and Researchers. London: SAGE, 1–26.
27.
Ryan AnneB. (2006) Post-Positivist approaches to research. In: Researching and Writing your thesis: a guide for postgraduate students. MACE: Maynooth Adult and Community Education, 12–26.
28.
ShentonAK (2004) Strategies for ensuring trustworthiness in qualitative research projects. Education for Information22: 63–75.
29.
SilvermanD (2011) Interpreting qualitative data: methods for analysis talk and interaction (fourth edition). London: SAGE.
30.
SnapeDSpencerL (2003) The foundations of qualitative research. In: RitchieJLewisJQualitative research practice: a guide for social science students and researchers, 1–23, London: SAGE
31.
ThomasDR (2006) A general inductive approach for analyzing qualitative evaluation data. American Journal of Evaluation27(2): 237–246.
32.
WarrenCA (2002) Qualitative interviewing. In: GubriumJFHolsteinJA (eds) Handbook of Interview Research: Context and Method. Thousand Oaks, CA: SAGE, 83–101.
