BIBS: Usage Statistics

(July 2002)


This page contains usage statistics about the system. These statistics augment the statistics given in the BIBS Report.

Most of these statistics were derived from analysis of the usage log recorded by the Real Media Server. The server writes a log record at the end of every session that includes information about the location of the player (IP Address), the file being played, the date and time when the file was played, the duration of the play in seconds, and the number of bytes delivered. BIBS records info about the class and lecture date in the file name so that we can determine which lecture is being played. This log is processed into a relational database on which further queries are run to compute the statistics reported below.

Many records show play durations of zero or only a few seconds. We interpret this to mean that either the session could not be started or that the user found the experience unusable. Consequently, we remove all entries where the play duration is shorter than 60 seconds before computing usage statistics. In the spring 2001 semester this removed more than 40% of the log entries. This failure rate is troubling but other researchers have found similar statistics when examining Real Networks logs.

Summary Usage By Semester

Semester # Classes # Plays Plays/Month Enrolled Students Plays/Enrolled Student
SP 1999 3        
FA 1999 7        
SP 2000 11 43,569 10,892 2,914 15
FA 2000 15 67,642 16,911 4,193 16
SP 2001 15 76,046 19,012 4,728 16
FA 2001 15 84,073 21,018 4,972 17
SP 2002 15 176,736 44,184 3,714 48

The following notes explain some of the numbers in this table.

  1. We do not have usage statistics for the Spring and Fall 1999 semesters.
  2. The statistics for Fall 2001 and Spring 2002 were reported by IS&T and Educational Technology Services who took over operation of BIBS that semester.
  3. During Spring 2002, approximately 18% of the plays (32,252) were made during finals. This confirms other data that shows students use the lecture webcasts primarily to study for examinations.
  4. The enrollment number for Fall 2000 only includes fourteen classes. Econometrics 244 was not offered that semester. The lectures viewed by students were recorded in a previous semester.
  5. A dramatic increase in viewing occurred in the Spring 2002 semester. The number of plays increased by a factor of two overall and by almost a factor of three for plays per enrolled student. Evidently the service is getting more popular and/or visible to the students.
  6. Viewing in Fall 2000 increased by roughly 10% with only a 5% increase in enrollments. This result could indicate that more students are watching the lectures or that more non-students are watching the webcasts.

Plays of What Semester Material

We find that every semester lectures from previous semesters are played. Some are for classes being offered in the current semester and some are for classes not being offered in the current semester, typically graduate classes. For Spring 2001, 13% of the plays were for material from a previous semester broken down as follows. The Summer 2000 plays (SU00) are for CS61A lectures that were recorded that summer.

Semester # Plays Percent of Total Plays
SP 99 39 0%
FA99 1,000 1%
SP00 3,074 4%
SU00 231 0%
FA00 5,457 7%
SP01 66,209 87%

Spring 2002 Plays Per Class

Class # Enrolled # Plays Plays/Enrolled
Student
# Live Plays % Live
Biol1B 467 30,468 65 x x%
Chem1A 506 9,080 18 x x%
CS3 165 2,788 17 x x%
CS61A 311 11,165 36 x x%
CS61B 251 11,137 44 x x%
CS61C 258 11,094 43 x x%
CS150 62 16,658 269 x x%
CS162 251 16,372 65 x x%
EE141 61 24,867 408 x x%
EE213 5 2,232 446 x x%
IAS 180 164 3947 24 x x%
IDS110 388 10,978 28 x x%
IDS114B 99 1,027 10 x x%
ME219 31 9,826 317 x x%
NS10 695 15,097 22 x x%

The following notes explain some of the strange numbers in this table.

  1. We use "plays/enrolled-student" to measure the popularity of the webcasts. Each class has between 30-45 lectures unless it is a seminar (e.g., IDS114B). Clearly, the "plays/enrolled-student" for CS150, EE141, EE213, and ME219 include too many plays for the number of students. These lectures are likely being played by many non-Berkeley students. Previous semesters, the non-Berkeley plays are estimated to be roughly 30% of all plays. The availability and popularity of these classes shows people want access to the Berkeley class lectures.
  2. We publish the lectures for anyone on the Internet to access for free. An experiment should be done to assess the potential for charging access to the material.

Spring 2001 Plays Per Class

Class # Enrolled # Plays Plays/Enrolled
Student
# Live Plays % Live
Biol1B 396 10,721 27 0 0%
Chem1A 385 8,031 21 269 3%
Classics 28 429 3,473 8 592 17%
CS3 287 2,633 9 144 5%
CS61A 446 8,134 18 1,051 8%
CS61B 335 8,035 24 737 11%
CS298-5 12 2,271 189 348 7%
EE241 26 1,092 42 23 2%
IDS110 462 5,995 13 675 11%
IDS114B 66 409 6 0 0%
MATH53 372 3,390 9 789 23%
ME219 50 1,786 36 85 5%
NS10 657 3,184 5 127 4%
PHYS8A 479 3,882 8 110 3%
PHYS8B 326 3,173 10 165 5%

The following notes explain some of the strange numbers in this table.

  1. CS298-5 is the Berkeley MIG Seminar which has a large audience outside the campus. This semester there were 14 seminars each of which was played an average of 162 times. The actual statistics for the seminars are:
    • minimum number of plays=35
    • median number of plays=120
    • maximum number of plays=419 (Jim Barton's talk on the TiVo architecture)
  2. IDS114B is also a seminar class, but it is less widely known since this is the first semester it has been offered. Nevertheless, each seminar was played on average of 29 times.
  3. Plays per enrolled student is typically higher for graduate classes (e.g., EE241 and ME219) because students at other universities and people in industry often watch the lectures.
  4. The high number of live plays for CS61A and CS61B, which are the first two classes in computer science, has been seen several semesters. This likely results from the familiarity of the students with computers and the desire to explore streaming media technology.
  5. The high number of live plays for MA53 and CLAS28 is surprising since this is the first semester these classes have been offered on BIBS.


Send comments to larry "dot" rowe "at" gmail "dot" com.
Last updated July 24, 2002.