Table 1.

 Instrument details, study details, and instrument characteristics and psychometric data

Instrument and study details				Instrument development and psychometric properties
Instrument name	First author, reference (year, country)	Version of scale used/context/temporal application	Description of instrument	Instrument development and item selection	Validity	Reliability
Anticipated Regret Questionnaire 37	Development: Godin 37 (2005, Canada) Evaluation: McMahon 47 (2008, Ireland)	Original (Godin) 37 /Health and Medicine/Longitudinal 37 Cross‐sectional 47	Original: 3‐item 5‐point rating scale (1 = very unlikely to 5 = very likely). Rate agreement with statement ‘if I did not give blood’: Item 1: I will regret it; Item 2: it would bother me; Item 3: I would be disappointed.	Regret definition: no specific definition provided. Used ‘Etic‐Emic’ approach: item to measure theoretical construct (etic) based on information obtained from population under study (emic). 1st version piloted and submitted for validity and reliability testing.	No data available	Internal consistency: Cronbach’s α = 0.87 2 week test‐retest reliability = 0.58 37 Cronbach’s α = 0.91 47
Anticipated Regret Scale 36	Development: Sheeran 36 (1999, UK)	Original (Sheeran) 36 /Business and Economics/Cross‐sectional	Original: 2‐item 5‐point rating scale (1 = strongly agree to 5 = strongly disagree). Rate agreement with statements using scale. Item1: If I missed playing the national lottery for 1 week I would regret it; Item 2: Not playing the national lottery for 1 week would upset me. Introduced different time periods in items and action version of instrument.	Regret definition: based on economic theories 48 , 49 . People compare outcomes of decisions. A person will experience (or anticipate) regret when the outcome of alternative is (or anticipated to be) more favourable than the outcome of the option chosen. Regret items part of larger questionnaire measuring constructs of the Theory of Planned Behavior 50 . No further information about development of the instrument or selection of items.	Discriminant and convergent validity demonstrated in 3 studies. Regret items load high on single factor with no cross‐loadings.	Internal consistency: Cronbach’s α = 0.85 (Study 1); α = 0.96 (Study 2); α = 0.83 (Study 3‐inaction scenario) and α = 0.94 (action scenario)
	Evaluation: Abraham 51 (2003, UK) Sheeran 52 (2003, UK)	Original (Sheeran) 36 /Psychology and Health/Cross‐sectional 51 Longitudinal 52	Same items as Original with different anchors (1 = definitely yes to 7 = definitely no)	N/A	Discriminant and convergent validity. Factor analysis revealed 2 factors. Regret items load high on a single factor with no cross‐loadings. 51	Internal consistency: Cronbach’s α = 0.82 (study 1); α = 0.63 (study 2) 51 Cronbach’s α = 0.68 52
	Rapaport 53 (2000, UK)	Modified (Rapaport) 53 /Psychology/Cross‐sectional	Modified: Additional item added to original instrument. 3‐item 7‐point rating scale. Item 1: 1 = strongly agree to 7 = strongly disagree. Item 2: 1 = regret to 7 = no regret. Item 3: 1 = upset to 7 = not upset).	Authors do not provide information or justification for the inclusion of another item.	Discriminant and convergent validity. Regret items load high on single factor with no cross‐loadings.	Internal consistency: Cronbach’s α = 0.82
Decision Regret Scale 15	Development: Brehaut 15 (2003, Canada) Evaluation: Davison 54 (2003, Canada); Davison 39 (2007, Canada); Feldman‐Stewart 55 (2004, Canada); Goel 56 (2001, Canada); Sheehan 40 (2007, Australia); Wakefield 57 (2008, Australia)	Original (Brehaut) 15 /Health & Medicine/Cross‐sectional	Original: 5‐item 5‐point scale (1 = strongly agree to 5 = strongly disagree). User reflects on relevant healthcare decision and rates statements using scale. Item 1: It was the right decision; Item 2: I regret the choice that was made; Item 3: I would go for the same choice if I had to do it over again; Item 4: The choice did me a lot of harm; Item 5: The decision was a wise one.	Regret definition: ‘Remorse of regret over a (health care) decision’ [15, p. 283]; ‘aspect of regret stemming from the knowledge that the choice made was non‐optimal…’[15, p. 282]; regret concerning a poor outcome. Agreed the definition of regret and developed pilot version. 3 items consistent with previous instruments and 2 new items. Iterative process of editing items and informal pilot testing. Several items dropped (no further information).	Assessed in 4 contexts. Construct validity – regret over poor outcome construct of interest. Found significant correlations between increased regret and poorer physical/psychological outcomes and quality of life. Convergent validity – found significant correlation between increased regret and decreased satisfaction with decision/doctor’s visit and increased decisional conflict 15	Internal consistency in 4 contexts 15 : (i) Hormone replacement therapy decision, Cronbach’s α = 0.92; (ii) Breast cancer therapy decision, α = 0.84; (iii) Breast cancer surgery decision, α = 0.86; (iv) Prostate cancer treatment decision, α = 0.81 Cronbach’s α = 0.83 54 Cronbach’s α = 0.91 39 Cronbach’s α = 0.90 40
	Diefenbach 58 (2007, USA)	Modified (Diefenbach) 58 /Health and Medicine/Longitudinal	Modified version 1: Selected 2 items from original instrument. Used different anchors. 2‐item 5 point rating scale (1 = not at all to 5 = very much).	Removed 3 items to reduce subjects’ burden. No further information.	Convergent validity – found significant correlation between regret and satisfaction with treatment decision and with decision conflict.	Internal consistency: Cronbach’s α = 0.47 (6 months); Cronbach’s α = 0.46 (12 months). Test‐retest reliability (6 months and 12 months): r = 0.53
	Diefenbach 59 (2008, USA)	Modified (Diefenbach) 59 /Health and Medicine/Longitudinal	Modified version 2: Selected 3 items from original instrument. Used different anchors. 3‐item 5 point rating scale (1 = not at all to 5 = very much).	Removed 2 items to reduce subjects’ burden. No further information.	PCA confirmed unidimensionality of 3 items.	Internal consistency: Cronbach’s α = 0.58
Experienced Regret Scale 43	Development: Keaveney 43 (2007, USA)	Original (Keaveney) 43 /Marketing/Cross‐sectional	Original: 3‐item 7‐point rating scale (1 = do not regret at all to 7 = regret very much). User reflects on specific decision and rates agreement with statements using scale. Item 1: How much happier would you have been, if you had made a different decision?; Item 2: How annoyed do you feel that you made a wrong decision?; Item 3: How much would you regret your decision to buy this vehicle?	Regret definition: regret is experienced when we would change an action we took (failed to take) as we can imagine that the outcome of the alternative would be preferable 60 Regret items part of larger questionnaire measuring pre‐purchase and post‐purchase stages of buyer decision‐making process. No further information about development of the instrument or selection of items. State they use items used in previous research.	Construct validity – Confirmatory factor analysis showed 21 items (3 regret) loaded highly on their corresponding factors. Convergent validity –t values on factor loadings ranged 15.80–16.28. Also examined with factor reliability. Average variance extracted = 0.64.	Internal consistency: Cronbach’s α = 0.95
Regret & Disappointment Scale 44	Development: Marcatto 44 (2008, Italy)	Original (Marcatto) 44 /Psychology/Cross‐sectional	Original: 2‐item 7‐point rating scale (1 = not at all/statement not pertinent to 7 = totally agree). Administered with regret scenario. User rates agreement with statements using scale. Item 1: I wish I had made a different choice; Item 2: I feel responsible for what happened to me. Also given 3rd item asking user to choose between 1 of 2 counterfactuals (regret or disappointment).	Regret definition: regret results from our ability to compare ‘what is’ with ‘what might have been’ & (unlike disappointment) has strong association with a feeling of responsibility 19 Regret items form part of a larger 7‐item instrument that also measures disappointment. Regret items selected from main cognitive antecedents of regret based on Camille’s definition 19	Construct validity – Study 1 – PCA confirmed 2‐factor structure (regret & disappointment). Significant interaction between regret scenario used and regret items in instrument. Study 2 – PCA confirmed 2‐factor structure from study 1. Binary logistic regression found Increased regret score was associated with choice of regret counterfactual. Study 3 – confirmed significant interaction from study 1 and binary logistic regression in study 2. Convergent validity – Significant correlation with the ‘Regret Scale’ 45	Internal consistency: Cronbach’s α = 0.64 (study 1)
Regret Experience Measure 20	Development: Creyer 20 (1999, Australia) Evaluation: Lin 62 (2006, Taiwan)	Original (Creyer) 20 /Marketing/Cross‐sectional	Original: 8‐item 7‐point rating scale (1 = disagree completely to 7 =  agree completely). Item 1: I regret my choice; Item 2: I think I made an error in judgment; Item 3: Before I received outcome feedback, I knew I had made an excellent decision; Item 4: I am confident I made the best choice based on the information I had available; Item 5: Before I should have chosen differently; Item 6: I knew that I should have chosen differently; Item 7: I feel really good about my choice.	Regret definition: general feeling that we would change our decision, if given the opportunity, a belief an error was made at the time of the decision, & sense of self‐recrimination. 49 , 61 Pool of 9 items generated that addressed 3 aspects of regret. Factor analysis revealed 1 factor structure. 1 item with low item to total correlation dropped. Factor analysis of 8 items revealed high positive correlations with the first factor.	Construct validity – Significant correlation between increased regret and increasingly negative feedback about outcomes (study 1 & 2). Factor analysis revealed high positive correlations with 1 factor (study 1 & 2). 20	Internal consistency: Cronbach’s α = 0.85 (study 1); α = 0.85 (study 2) 20 Unclear if evaluation study 62 reports new psychometric data or data from original study.
Regret Scale 38	Development: Clark 38 (1997, USA)	Original (Clark) 38 /Health and Medicine/Cross‐sectional	Original: 3‐item rating scale. Item 1: 6 point rating scale (1 = all of the time to 6 = none of the time). Have you wished that you could change your mind about the kind of treatment you chose for you prostate cancer? Item 2 & 3: 5 point rating scale (1 = definitely true to 5 = definitely false). Item 2: feel that I would be better off if I had chosen the other treatment for prostate cancer. Item 3: It bothers me that other men with prostate cancer get treatment that Is very different from what I have received.	Regret definition: uncertainty over choice made, a wish to reverse the decision, & feeling that one would be better off if the other option was chosen. Regret items form part of a larger 9‐scale instrument that addresses indicators of quality of life of men with metastatic prostate cancer. Focus group transcripts analysed to identify themes of patients’ experiences after treatment. 65 candidate items developed piloted. PCA performed on each theme. Items with low communality & those that cross‐loaded were deleted. PCA identified 9 dimensions of quality of life, including regret.	Construct validity – PCA confirmed regret items load on 1 factor. Regret scale able to discriminate between 2 groups. Regret scores lower (worse outcome) in patients who reported many symptoms. Discriminant validity – Significant correlation between regret scale and the other sub‐scales suggest it measure a different quality of life.	Internal consistency: Cronbach’s α = 0.80
	Evaluation: Clark 9 (2001, USA) Hu 10 (2003, USA)	Modified (Clark) 9 /Health and Medicine/Cross‐sectional	Modified: Selected 2 items from Original instrument. Used Item 1 & 2. Used same scaling and anchors.	Item 3 that defined the internally consistent original instrument added little information and was removed.	No data available	No data available
Regret Scale 8	Development: Clark 8 (2003, USA) Evaluation: Clark 63 (2003, USA)	Original (Clark) 8 /Health and Medicine/Cross‐sectional	Original: 5‐item instrument. No information about item scaling or anchors. Users rates statements using scale. Item 1: I wonder if I would have been better off with a different treatment; Item 2: I sometimes wonder whether it was really worthwhile being treated at all; Item 3: I sometimes feel that the treatment I had was the wrong one for me; Item 4: If I had to do it over, I would choose some other treatment; Item 5: I sometimes wish I could change my mind about the kind of treatment I chose for my prostate cancer.	Regret definition: a feeling of having made the wrong treatment choice, persistent doubt, & the wish to change the decision. Regret items form part of a larger 11‐scale instrument that addresses indicators of quality of life of men with early stage prostate cancer. Focus group transcripts analysed to identify themes of patients’ experiences after treatment. 84 candidate items developed piloted. PCA performed on each theme. Items with low communality & those that cross‐loaded were deleted. Psychometric analyses defined 11 scales, including regret.	Discriminant validity – Correlations between the 11 scales were consistent with pattern of item‐scale discrimination. 8	Internal consistency: Cronbach’s α = 0.81 8
Regret and Maximization Scale 45	Development: Schwartz 45 (2002, USA) Evaluation: Parker 64 (2007, USA) Saffrey 34 (2008, Canada)	Original (Schwartz) 45 /Psychology/Cross‐sectional	Original: 5‐item 7‐point rating scale (1 = completely disagree to 7 = completely agree). Users rate agreements with statements using scale. Item 1: Whenever I make a choice, I’m curious about what would have happened if I had chosen differently. Item 2: Whenever I make a choice, I try to get information about how the alternatives turned out. Item 3: If I make a choice and it turns out well, I still feel like something of a failure if I find out that another choice would have turned out better; Item 4: When I think about how I am doing in life, I often assess opportunities I have passed up; Item 5: Once I make a decision, I don’t look back (reversed).	Regret definition: no specific definition provided but state regret may result from non‐optimal choice. Regret items from part of a larger 18‐item instrument that also measures maximization. Preliminary 42‐item instrument (9 items measuring regret) created. On basis of reliability and face validity, instrument reduced to 22 items (5 regret items). Presented to 11 judges. 4 regret items judged by 10/11 to be about regret and 1 item judged by 9/11 to be about regret. 22 items (5 regret) submitted to a PCA.	Construct validity – Regret items loaded highly on single factor. Convergent validity – Significant positive correlation between regret and maximization. 45 Convergent validity – Significant positive correlation between regret and maximization 64	Internal consistency: Cronbach’s α = 0.67 45 Cronbach’s α = 0.76 64 Cronbach’s α = 0.67 (when using scale on self); α = 0.77 (when using scale for other). 34
Regret Measurement 46	Development: Tsiros 46 (1998, USA) Evaluation: Huang 65 (2007, China) Hung 66 (2007, China)	Original (Tsiros) 46 /Business and Economics/Cross‐sectional	Original: 2‐item 7‐point rating scale (−3 = strongly disagree to 3 = strongly agree). Administered with hypothetical scenario. User rates agreement with statements using scale. Item 1: I feel sorry for having chosen company ALPHA; Item 2: I feel regretful for having chosen company ALPHA.	Regret definition: regret is the unpleasant feeling of finding out that the alternative option would have led to better outcomes 48 , 49 Regret items form part of a larger questionnaire that also measures satisfaction. Limited information about item selection. State 7‐point rating scales were used on the basis of reported literature. Subjected to reliability and validity testing to determine final instrument.	Construct validity – 2 regret items loaded highly on a single factor. Discriminant and Convergent validity – demonstrated using a correlation matrix of individual items 46 Content validity confirmed by authors. Convergent and Discriminant validity – regret items load high on different factor to satisfaction. 66	Internal consistency: Cronbach’s α = 0.82 46 Cronbach’s α = 0.86 65 Cronbach’s α = 0.85 (study 1); α = 0.74 (study 2) 66
	Pierro 67 (2008, Italy)	Modified (Pierro) 67 /Marketing/Cross‐sectional	Modified version 1: Selected 2 items from previously modified instrument 64 and added additional item. 3‐item 7‐point rating scale. Items 1 & 2: 1 = not at all to 7 = very much. Item 3: 1 = not at all – 7 = definitely.	Removed item 3 from previously modified scale. 68 No information about removal and selection of new item.	Construct validity – Found significant difference between difference groups (study 1 & 2)	Internal consistency: Cronbach’s α = 0.85 (study 1); α = 0.74 (study 2)
	Tsiros 68 (2000, USA)	Modified (Tsiros) 68 /Marketing / Cross‐sectional	Modified version 2: Additional item added to original instrument. 3‐item 7‐point rating scale (1 = strongly agree to 7 = strongly disagree).	Regret items form part of a larger questionnaire that also measures satisfaction. Used 2 items from original instrument. Used 1 additional item from another un‐validated instrument. Selected item as it addressed regret. Other items excluded as they addressed cognitive dissonance and re‐purchase intentions.	Construct validity – Factor analysis revealed 2 factors. Regret items loaded high on regret factor and low on satisfaction factor, and vice versus. Discriminant validity – Examined dimensionality of 6 items (3 regret, 3 satisfaction). Confirmatory factor analysis revealed 2‐factor solution better than 1.	Internal consistency: Cronbach’s α = 0.82