Performance has declined during the 2004-2010 time period.
Cf. SF Muni Metro Performance Graphs.

On-time performance Date J Church K Ingleside L Taraval M Oceanview N Judah Average or Total Jul-Dec 2004 80% 81% 76% 70% 79% 77% Jan-Jun 2005 57% 72% 79% 71% 69% 70% Jul-Dec 2005 54% 75% 87% 65% 83% 73% Jan-Jun 2006 70% 69% 64% 61% 69% 67% Jul-Dec 2006 61% 68% 72% 73% 73% 69% Jan-Mar 2007 71% 81% 71% 74% Apr-Jun 2007* 74% 72% 2004-2007 average 66% 74% 75% 69% 74% 72% standard deviation 10% 6% 8% 5% 6% 4% daily riders in thousands 19 15 23 23 31 112 scheduled time for route in minutes 44' 36' 35' 43' 38' 40' *The T line began service in April, 2007

Runs operating within scheduled headways Date J Church K Ingleside L Taraval M Oceanview N Judah Average or Total Jul-Dec 2004 62% 100% 90% 44% 50% 69% Jan-Jun 2005 55% 100% 100% 79% 41% 75% Jul-Dec 2005 37% 56% 82% 57% 60% 58% Jan-Jun 2006 49% 57% 41% 67% 58% 54% Jul-Dec 2006 37% 54% 52% 67% 62% 54% Jan-Mar 2007 42% 76% 61% 65% Apr-Jun 2007* 60% 88% 2004-2007 average 47% 74% 71% 63% 60% 63% standard deviation 10% 22% 23% 12% 16% 8% daily riders in thousands 19 15 23 23 31 112 scheduled time for route in minutes 44' 36' 35' 43' 38' 40'

On-time performance Date J Church K Ingleside -T Third L Taraval M Oceanview N Judah Average Jul-Dec 2007 67% 75% 79% 59% 69% 70% Jan-Jun 2008 n.a. 74% 70% 72% 65% n.a. Jul-Dec 2008 62% 61% 70% 62% 73% 66% Jan-Jun 2009 72% 68% 73% 70% 68% 70% Jul-Dec 2009 72% 84% 73% 68% 78% 75% Jan-Jun 2010 76% 70%# 77%# 68%# 80% 74% 2007-2010 average 70% 72% 74% 67% 72% 71% standard deviation 5% 8% 4% 5% 6% 4% Jul-Dec 2010 77% 54% 70% 62% 72% 71% Jan-Jun 2011 66% 58% 70%# 67%# 78%# 68% scheduled time for route in minutes* 35' 73' 36' 40' 47' 44' * The changes in time from 2004-7 are due to several changes in routes. The K and T lines are combined. # Calculated from FY Q1, Q2, and average figures.

Runs operating within scheduled headways Date J Church K Ingleside -T Third L Taraval M Oceanview N Judah Average Jul-Dec 2007 74% 75% 66% 62% 50% 65% Jan-Jun 2008 n.a. 56% 53% 60% 46% n.a. Jul-Dec 2008 42% 40% 50% 49% 53% 47% Jan-Jun 2009 53% 48% 54% 44% 35% 47% Jul-Dec 2009 49% 66% 58% 62% 47% 56% Jan-Jun 2010 50% n.a. n.a. n.a. 82% n.a. 2007-2010 average 54% 57% 56% 55% 52% 54% standard deviation 12% 14% 6% 8% 16% 9% Jul-Dec 2010 n.a. 44% 66% 53% n.a. n.a. Jan-Jun 2011 48% 45% n.a. n.a. n.a. n.a. scheduled time for route in minutes* 35' 73' 36' 40' 47' 44' * The J ends at Embarcadero instead of 4th and King Streets. The N ends at 4th and King Streets rather than the Embarcadero.

San Francisco Muni checks its performance once in every six month period for each line.  Muni data is posted at SFMTA;  however, as of 1/15/13, the last Muni update was on 8/17/11.  Ridership numbers are from sfgate.com. The Muni goal is to have at least 85% of vehicles run on time according to published schedules, no more than 4 minutes late or 1 minute early.  According to an article in the Bay Citizen, Muni has actually considered 4 minutes 25 seconds late as being "on time" and since 2010, 4 minutes 59 seconds has been considered "on time". The Muni goal is to have at least 85% of vehicles within the lesser of 30% or 10 minutes of scheduled headway (interval between trains in minutes). Using linear regression, there has been a gradual decline in the average headway for the Muni Metro system during the 2004-2010 time period;  average on-time performance has declined slightly from 71% to 70%  Muni Metro performance graphs. Headway, the interval between trains, is more important to most passengers than the on-time performance.  Most passengers do not carry schedules and the schedules are not posted at Muni stops.  If a train is scheduled to arrive every ten minutes, for example, and every train is five minutes late, the interval between trains would still be every ten minutes. The results for headway between trains are worse than those for on-time performance in the above data.  This may be because the criteria for headway are stricter than the criteria for on-time performance in many cases. A train is not considered late unless it is at least four minutes behind schedule. As the scheduled headway during commute hours ranges from seven to ten minutes for the Metro system, a train that is two to three minutes late may not meet the criteria for headway.