Читать книгу Demystifying Research for Medical and Healthcare Students - John L. Anderson - Страница 34

The simplest experimental design is what we call a single arm experiment – see Figure 2.1. Most science lab experiments probably fall into this category. However, most experiments involving humans are twin’, or ‘double‐arm experiments (Figure 2.2). Some are triple or more (Figure 2.3). Single‐arm experiments do not have a control group, whereas twin‐arm and triple (or greater) experiments do have a control group. Some experimental designs have more than two groups, but more of this later. There was a tradition in the nineteenth century for scientists to try things out on themselves first of all. There is still an element of this ‘gung‐ho’ culture in modern science – which ethics committees try to keep in check.

FIGURE 2.1 Single arm experiment.

FIGURE 2.2 Twin arm experiment.

FIGURE 2.3 Triadic design with yoked controls.