I am trying to arrange a speakers schedule that allows for a fair
rotation while allowing for members to be deleted or added as they
join or quit the group.  Currently there 26 members in the group.  We
meet weekly and each week 2 speakers speak for 10 minutes.  The person
who previously arranged the schedule simply paired the same two
speakers together each time the rotation came around.  Boring.  Also,
if someone dropped out of the group, that slot would just be left
empty and there was no mechanism to fill the slot until the end of the
3 month rotation and then she would re-do the whole schedule again. 
It would still be the same 2 speakers except where someone dropped
out.  Then the new member would usually just fill that slot.  There
has got to be a better way that can be easily understood by the person
generating the schedule as well as the speakers.  Note: when I say
easily understood, the position I currently occupy only lasts 6
months. Therefore it has to be something that can easily be followed
by someone reviewing a couple short paragraphs of instructions.

I tried creating 2 columns (odd/even) and simply rotate the odd column
up or down one.  The problem with this is that if I rotate the odd
column up (so the first speaker on the list goes to the end of the
list) then the person who is at the top of the list has to (currently)
wait a full 25 weeks to be able to speak again.  Or if I rotate the
odd column down, the last speaker on the list would be the first
speaker again on the new rotation meaning they would speak 2 weeks in
a row.

There has got to be an:
1. easy and understandable way to 
2. rotate 2 speakers per meeting while never having the same 2 speakers at the
same time, 
3. allow for inserting or deleting speakers as needed, 
4. and keep it fair by keeping the spacing of the speakers even.

Whew!  Does that make sense?  If you can help I would appreciate it. 
If not, pray for me.  LOL

Anthony

What about just one alphabetical list of the speakers, thus a
replacement will probably not be in the slot of the person dropping
out, but no matter.

Then pick two random digits. (The last digit on the number on a bank
notes is the way internal auditors pick random numbers.)  If these are
not the same, those are your first two speakers.  If they are, you
start with the "second" speakers under the following step.

Then prepare a table, names on column one, dates across the top. 
Starting with the first starting speaker, count down three to pick the
first one for the next meeting.  For the second speaker at the next
meeting, count down five from the second starting speaker.  Continue
this pattern for the following meetings.

The use of odd numbers, since 26 is not divisable by 3 or 5, will
assure eventually everyone on the list will have his/her turn as
"first" and "second" speaker (and that no one will be skipped, which
would happen by using an even number).
At some point, this rotation schedule will, of course, result in one
person's being "hit" by both systems, but not often, I believe.  It
could occur fairly soon, depending on the random numbers, of course.
(Give him/her a bottle of champagne and let him/her speak for twenty
minutes. :)  OR start your dates after this has occurred.)  I don't
think repeated pairs of speakers will be a problem.

OF course, I am only envisaging this system, so maybe this doubling up
can occur more often than I think.  And, it probably won't assure
equal spacing of the speakers.    Hmmm?

With hindsight, I revise my idea of inserting new members
alphabetically.  Seems unnecessary and to require revamping of the
whole schedule.  Just replace their name for that of the person
resigning.

More "Hmmm"?   I guess a trial schedule would be necessary to see how
this works out.  Maybe counting by 3 and 7 (or 11) would give better
spacing.

It's been fun.  Hope it helps.  Let us know.

Myoarin

Next suggestion?