Ztree

z-Tree is a recent stand-alone program for Microsoft NT that offers an integrated development environment for experiments. An important advantage of Ztree is the ability to develop experiments within days, sometimes within hours. However, since it is restricted to Microsoft NT and derivatives (Microsoft 2000, Microsoft XP, etc.). I discuss my experience with running z-Tree under wine on a non-Microsoft OS in a seperate document.

In any case, requiring nothing but a WWW browser for your experiments is often less problem-prone.

Also the interface and programming language of z-Tree offer some restrictions.

• Graphics can only be used from z-Tree 3 onwards, which is currently (2004) still $\alpha$. However, the current 3$\alpha$ version is already quite reliable.

  It is not possible to show pictures, though.

• z-Tree divides experiments into treatments. Each treatment has to be started manually. This means that some intervention of the experimenter is needed during sessions.
• User definable functions, procedures or macros are not implemented. This makes programming sometimes clumsy.
• Variables can only be real numbers. It is, still, possible to print text on the screen, even conditional on the value of variables, but it is not possible for participants to enter text, except in a last treatment, a so called ``questionnaire''.
• z-Tree measures time only as small as a second.

Still, for many experiments where participants are physically within the lab z-Tree may be the ideal platform.