Usage of edit summary on Wikipedia

Some statistics on edit summary usage: percentage of edits to main namespace with some edit summary, from January 1, 2005 to June 30, 2010. Query on en.wiki killed after 48 hours of execution. The aim of these statistics was to evaluate the effect of the introduction of some default buttons which contributors can use to add standard edit summaries to their edits. Statistics suggest that buttons increase the percentage by about 10 points compared to other wikis and same wiki before their introduction, except for ukwiki where they didn't have any clear effect and plwiki where they didn't have any additional effect after a previously introduced warning.

(Italian) Percentuale utilizzo campo oggetto nelle modifiche del namespace principale dal 1° gennaio 2005 al 30 giugno 2010 sulle principali wiki. È esclusa enwiki in quanto ho dovuto interrompere la query dopo quasi 48 ore di esecuzione.

wiki	%
plwiki	88.25
skwiki	88.12
frwiki	79.82
nlwiki	79.67
dewiki	78.33
ruwiki	74.80
itwiki	73.96
eswiki	72.33
jawiki	72.21
ptwiki	71.89

Buttons introduction effects

plwiki

Buttons have been introduced ~~on March 17, 2007~~ in October 2006. Additionally, anonymous editors who don't enter an edit summary are shown a warning when they first hit "save" (the edit summary text area is selected and encircled with a red rectangle), since April 2006.

(Italian) I pulsanti sono stati introdotti il 17 marzo 2007.

year-month	%
2006-01	71.84
2006-02	61.78
2006-03	69.20
2006-04	78.07
2006-05	78.10
2006-06	82.35
2006-07	79.85
2006-08	85.82
2006-09	81.10
2006-10	78.07
2006-11	77.28
2006-12	77.73
2007-01	80.96
2007-02	76.90
2007-03	81.99
2007-04	90.35
2007-05	91.22
2007-06	90.62
2007-07	86.64
2007-08	89.66
2007-09	91.78
2007-10	92.18

Anonymous editors who enter an edit summary:

year-month	%
2006-04	53.77
2006-05	62.71
2006-06	61.75
2006-07	56.94
2006-08	57.66
2006-09	56.90
2006-10	54.27
2006-11	46.87
2006-12	54.23
2007-01	51.97
2007-02	52.68
2007-03	64.08
2007-04	82.11
2007-05	83.78
2007-06	82.43
2007-07	61.73
2007-08	76.15
2007-09	81.37
2007-10	81.69
2007-11	83.78
2007-12	83.56
2008-01	83.23
2008-02	83.09
2008-03	85.36
2008-04	84.26

skwiki

Apparently, buttons have been introduced on August 27, 2008, but statistics suggest that they were introduced somewhere else on June 2006.

(Italian) I pulsanti dovrebbero essere stati introdotti il 27 agosto 2008. I dati, però, sembrano suggerire che siano stati introdotti nel giugno 2006.

anno-mese	%
2005-10	65.12
2005-11	65.61
2005-12	73.92
2006-01	65.96
2006-02	64.13
2006-03	77.64
2006-04	79.88
2006-05	70.08
2006-06	89.10
2006-07	83.90
2006-08	83.85
2006-09	86.65
2006-10	90.58
2006-11	86.59
2006-12	89.86
2007-01	90.08
2007-02	90.58

sk.wiki since 2007 is above 85% and since 2008 it's above 90%.

(Italian) Dal 2007 in avanti la percentuale è superiore all'85% e dall'inizio del 2008 è superiore al 90%.

hewiki

Standard edit summaries buttons were introduced on March 16, 2006.

year-month	%
2005-03	58.96
2005-04	56.15
2005-05	59.13
2005-06	56.85
2005-07	60.69
2005-08	62.28
2005-09	70.51
2005-10	66.24
2005-11	70.86
2005-12	75.42
2006-01	59.27
2006-02	62.62
2006-03	68.07
2006-04	71.87
2006-05	69.44
2006-06	72.22
2006-07	71.46
2006-08	69.77
2006-09	67.39
2006-10	70.77
2006-11	73.08
2006-12	74.48
2007-01	75.27
2007-02	75.64
2007-03	78.30

ukwiki

Standard edit summaries buttons were introduced on September 7, 2007.

year-month	%
2006-09	51.17
2006-10	59.30
2006-11	74.17
2006-12	65.80
2007-01	72.22
2007-02	76.98
2007-03	82.92
2007-04	66.97
2007-05	67.56
2007-06	64.16
2007-07	74.98
2007-08	70.01
2007-09	69.79
2007-10	73.96
2007-11	73.68
2007-12	73.98
2008-01	70.66
2008-02	71.97
2008-03	69.93
2008-04	67.09
2008-05	71.82
2008-06	74.67
2008-07	73.37
2008-08	67.95
2008-09	71.32