ə and ɜ have the exact same features

@DanielSWolf -- indeed. This is a problem that we are aware of (hence the "should"). The problem is also pervasive.

library(tidyverse)
df <- read_csv(url('https://raw.githubusercontent.com/phoible/dev/master/data/phoible.csv'))
df <- df %>% select(7:48, -Allophones, -Source, -Marginal, -SegmentClass) %>% distinct()
df <- df %>% remove_rownames %>% column_to_rownames(var="Phoneme")
df <- df %>% filter(tone != "+")
df <- rownames_to_column(df, "Phoneme")
out <- df %>% group_by(tone, stress, syllabic, short, long, consonantal, sonorant, continuant, delayedRelease, approximant, tap, trill, nasal, lateral, labial, round, labiodental, coronal, anterior, distributed, strident, dorsal, high, low, front, back, tense, retractedTongueRoot, advancedTongueRoot, periodicGlottalSource, epilaryngealSource, spreadGlottis, constrictedGlottis, fortis, raisedLarynxEjective, loweredLarynxImplosive, click) %>%
  summarize(phonemes = paste0(Phoneme, collapse = ', '), count = n()) %>% ungroup()
out %>% select(phonemes, count) %>% filter(count > 1) %>% arrange(desc(count))

   phonemes                       count
   <chr>                          <int>
 1 t, t͉, t̠, t̺, t̟, d̥, t̪̺, d̺̥, t̺͉          9
 2 t̻s̻, t̪s̪, ts̪, t̪s, t̪̻s̪̻, t̟ʃ̟, ts̻, t̻s̪̻     8
 3 t̠ʃ, t̠ʃ͉, t̠͉ʃ, d̥ʒ̥, t̻ʃ̻, d̥ʒ̊, ʈ̻ʂ̻         7
 4 ts, t͉s, t̺s̺, t̟s̟, d̥z̥, d̺̥z̺̥, ts̺         7
 5 d̻z̻, d̪z̪, dz̪, d̪ʒ, d̟ʒ̟, d̪z, dz̻         7
 6 ʃ, ʃ͉, ʒ̊, s̠, s̺̠, s̻̠, ʂ̻                7

There are several reasons for this, including but probably not limited to:

no features for tones (that's why I filter them out above)
some phoneme specifications in different documents collapse the feature vectors across phonemes, e.g., ʃ vs ʒ̊
some clicks are difficult to specify with the current feature set
plain mistakes that we need to revisit
the feature set itself requires some updates

@drammock anything else?

We should make this clearer in the FAQ and on the FEATURES page.

phoible / dev

ə and ɜ have the exact same features #352