In short we don't. At least we mostly don't. The various online tests require users to provide a name, DOB and company. This is simply so that when you complete an online test you can print off a progress record with your details on it. This information must be entered each time you undertake an online test as we do not save these details anywhere once you leave the test.
Our web service provide and google analytics will collect some information but this should not include anything that can be used to identify you as an individual.
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