recodes the PSS items depending on positive or negative wording item 1, 2, 3, 6, 9 and 10 need levels from 0 = "Never" to 4 = "Very often" item 2, 4, 7 and 8 need levels from 4 = "Never" to 0 = "Very often" function recodes items to needed levels
recode_pss(pss.factor, version)