PPD: Percentage of People Dissatisfied (PPD).
_
Specifically, this is defined by the percent of people who would have
a PMV beyond acceptable thresholds (typically <-0.5 and >+0.5).
I have doubts about the “wording” of the bold part above:
Is it describing the value of PMV, the percent of people, or the number of PPD thresholds?
The wording is correct.
Fanger used a normalized distribution to relate the Predicted Mean Vote (from -3 to +3) of his subjects in a climate chamber to the percentage of those subjects who report that their vote is not 0 (neutral). That percentage of “non-neutral” subjects is what PPD is.
When the PMV is perfectly zero (neutral), ~5% of Fanger’s subjects still reported a vote that was not neutral (either -1 or +1). When the PMV is +0.5, ~ 10% of the subjects report a value other than neutral (typically +1 in this case).
Maybe these graphic makes it clearer.
