Estimating the number of attendees for single events

How should we deal with events which are for free / included in the main fee such as conference workshops or sessions and for which we want to estimate the number of persons who will be attending?

We want to be able to get a fairly accurate estimate on the number of attendees so that we can assign sessions to venues with enough seating capacity.

(A German version of this article is available.)

If you want to get a fairly accurate estimate of people who will be attending sessions or workshops, then use the participant registration module of ConfTool to let participants register for these events.
Please skip to the next answer if you are only using the module for submission and reviewing of papers.

You find a manual on how to create the participant registration form here:
Configuration of the Participant Registration Module

For the sessions / workshops, first create new event groups here, representing time slots:
Overview => Settings => Manage Event/Item Groups
Usually, only one session / workshop can be chosen within each time slot.
Hence, for the option "Selection Mode" choose the setting "Exclusive: Use radio buttons so that only one event of this group can be selected" (see image 1).

Then create individual events for each session / workshop here:
Overview => Settings => Manage Events and Items
For the option "Price Category" make sure to choose the setting "No costs apply" (see image 2).
Please be aware that radio buttons cannot be unselected, therefore create an additional event for people who do not wish to attend a session / workshop (see image 3).

Another option to get a tally of the number of participants for sessions would be the "My Agenda" function of ConfTool:
Is it possible to allow users to create their personal agenda in ConfTool Pro?

This option is especially helpful when you want to know the number of attendees for sessions, but you have not booked the ConfTool module for participant registration.
Furthermore, you do not need to list sessions or workshops which are already in the agenda once again in the participant registration form.