ANY-maze Help > The ANY-maze reference > The Protocol page > The elements of a protocol > Testing > Stages > Setting up a stage > Specifying how the animals should be assigned to the apparatus in this stage

Specifying how the animals should be assigned to the apparatus in this stage

In brief

If your protocol includes multiple apparatus, for example two water-mazes, then you can specify for each stage the way that ANY-maze assigns the animals to the apparatus for the tests in the stage. There are three options:

Pre-assign

The first animal is assigned to the first piece of apparatus, the second animal to the second, etc., until all the apparatus has one animal assigned to it. The next animal is then assigned to the first piece of apparatus again and so on.

First available

The animals are only assigned to the apparatus immediately before their tests. The next animal to test is simply assigned to the first piece of apparatus which is free (i.e. has no test running in it.)

Same as previous stage

This option is only available in the 2nd stage and above. The animals are tested in the same piece of apparatus in which they were tested in the previous stage.

Details

In the simple case of pre-assigning the animals to apparatus, animal 1 will be assigned to the 1st piece of apparatus, animal 2 to the 2nd, animal 3 to the 1st, etc. (assuming just 2 pieces of apparatus) - see figure 1.

Figure 1. Animals 'pre-assigned' to two water-mazes.

While this simple assignment system seems very logical, it might be rather inefficient if tests can last for unequal durations and/or you are using some stage end rules. In these cases, it's possible for all the tests to end in one piece of apparatus while there's still a queue of animals waiting to be tested in another. To avoid this, you can choose to assign animals to the first available piece of apparatus. In this case, you won't know beforehand which piece of apparatus an animal will be tested on; it will just go to whichever one is free when its turn to be tested comes round - see figure 2.

Figure 2. Animals being assigned to 'the first available maze'. This is makes more efficient use of the mazes, although it can lead to an 'unbalanced' experiment with more animals being tested one piece of apparatus than the other.

An important point to understand is that if a stage includes multiple trials, the animals will be assigned to a piece of apparatus in their first trial in the stage using the rules described above; they will then be tested on the same apparatus in all the other trials in the stage.

In most cases where a protocol consists of more than one stage, you will probably want to ensure that an animal which was tested on one particular piece of apparatus in the first stage is tested on the same apparatus in all its subsequent stages - in this case, you should choose the assignment option Same as previous stage for the second and subsequent stages.

ANY-maze help topic T0396