The reason why there are two research hypotheses

In this book all research questions are addressed and then answered via the construction of two research hypotheses, commonly called the null hypothesis and the alternate hypothesis. (Although another name for the alternate hypothesis, the research hypothesis, has its own appeal, we employ the commonly used term alternate hypothesis in this book.) Both of these hypotheses are key components of the procedure of hypothesis testing. This procedure is a statistical way of doing business. It is described and discussed in detail in Chapter 6, but it is beneficial to introduce the main concept here. 

The null hypothesis is the crux of hypothesis testing. (It is important to note that the form of the null hypothesis varies in different statistical approaches. As the main type of clinical trial discussed in this book is the therapeutic confirmatory trial, we talk about this first. We then talk briefly about the forms of the null hypothesis that are used in other types of trials in Section 3.10.) As noted earlier, therapeutic confirmatory trials are comparative in nature. We want to evaluate the efficacy of the investi- 

The alternate hypothesis reflects the alternate possible outcome of the trial, and therefore the alternate possible answer to the research question The trial was conducted with the specific goal of providing an answer to the research question. In a superiority trial the alternate hypothesis takes the following form  

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