Whenever we have looked at this, there is very little difference between intensity versus frequency ratings. We have some papers on this if interested. Regarding positive affect, it’s hard to know what frequency would be better than intensity, but we welcome others to study it.

Chang and Salsman papers both show essential equivalence (the main finding), with one slightly favoring frequency and the other slightly favoring intensity (severity).

Chang, C-H., Cella, D., Clarke, S., Heinemann, A.W., von Roenn, J.H., Harvey, R. (2003). Should symptoms be scaled for intensity, frequency, or both? Palliative & Supportive Care. 1, 51-60

Salsman, J.M., Schalet, B.D., Andrykowski, M.A., & Cella, D. (2015). The Impact of Events Scale: A comparison of frequency and severity approaches to measuring cancer-specific distress. Psycho-Oncology. 24(12):1738-1745

Lai, JS, Butt, Z., Cella, D. (2011) Comparisons of Frequency and Intensity Based Perceived Cognitive Function Using Item Response Theory Models. Paper presentation at European Survey Research Association (ESRA).

Sharing some content that were included in this paper (Lai, JS, Butt, Z., Cella, D.; 2011):

Lai, J-S., Zelko, F., Butt, Z., Cella, D., Kieran, M., Krull, K., Magasi, S., Goldman, S. (2011) Perceived cognitive function reported by parents of the United State pediatric population. Child’s Nervous System, 27 (2), 285-293 (PMID: 20652814)

No item-pair had a residual correlation greater than 0.15, suggesting local independence (i.e., no redundant items from a measurement’s perspective) among these 44 items. Particularly for the 13 item pairs, which shared the same item content but used two types of rating frameworks, all but two had residual correlations less than 0.1 (range: 0.002 -0.084). Two exceptions were 0.147 and 0.126 but still less than 0.15. These results indicated for these items, two different rating scales did provide different perspectives in children’s cognitive function in their daily lives.

In terms of positive affect (i.e., Positive Illness Impact item bank), following texts were included in an earlier version of a paper which is under review. We played around a better way to ask but do not recall we ever considered using a frequency rating scale.

. . . . Subsequently, we conducted additional cognitive interviews with cancer survivors to help identify an item format that would best capture psychosocial illness impact. After consultation with multidisciplinary experts on the PROMIS Psychosocial Illness Impact Domain Working Group, we chose three item formats for this second wave of cognitive interviews: (1) the original item stems and response options, (2) the original stems with expanded response options to reinforce the illness attribution (e.g., 1=“yes a little because of my illness”), and (3) a two-part (before/after) item that includes each item stem (e.g., “unhappiness with my physical appearance”) followed by two questions (”How much before your illness” & “How much after your illness?”; each 0-4, “not at all” to “very much”).