Preliminary Data serve two purposes in a grant application. The first is to establish feasibility at the conceptual level. The second is to establish feasibility at the technical level.  Each goes in a different location in an R01 application.

In Approach, before Aims

For most grant applications there is some key bit of data that must exist for the experiments proposed within the application to make sense. This bit of data should be placed prominently, early in the approach section of the research strategy before going into the first aim. The figure showing this data should be large and have a clear legend describing the data thoroughly.

The primary preliminary data figure should be accompanied by a paragraph of text contextualizing the data in the existing literature and explaining its significance and implications. You should feel free to use previously published data in this figure. Attribute published data in the legend. Often a key preliminary data figure will contain a mix of new data, data previously published by the same group, and/or data from published sequencing, genetic screens, or other experiments. The sole purpose of this figure is to show, unequivocally, that the core assumptions of your grant proposal are valid. This data should be explicitly referenced in the abstract and in specific aims.

Within an Aim

Within each aim, conceptual preliminary data that establishes key facts necessary for the aim to be true should be placed early within the aim, before getting into details on the proposed experiments. These data should also include a clear and thorough legend, and be clearly explained in the grant text.

The other use of preliminary data is to establish that you have the technical expertise and equipment to perform a particular experiment. If you've published with a nonstandard technique, state that clearly and provide the reference. If you haven't, include a figure with proof of concept data showing that you can accomplish what is needed. Examples of this type of data could be a new sequencing technique or fancy imaging modality. Validating an animal model or showing preliminary hits from a screen would also fit.

General Guidelines

Make sure figures are large enough to read, labeled clearly, at sufficient resolution, and contain a clearly written legend. It is also smart to include alt text (in Word, right click on the figure to access alt text) describing the figure for anyone reading your grant that may have a disability. 

The legend of a preliminary data figure is very important. Each figure legend should start with a declarative statement clarifying the meaning of the data, not the technique. "[Key gene] is mis-spliced in disease" not "measurement of splicing fidelity in different cell lines". A

fter this statement, go into each panel comprising the figure and state what you are showing, how to read the data, and what it means. For example, "RT-qPCR data showing expression of gene X in mouse liver extract after 1, 3, 5, and 10 days of treatment with drug X. Expression peaks at day 5. N=5 mice, average and standard error plotted." Many reviewers will flip through a grant and just read the figures, so they should be able to be interpreted independently of the surrounding text. 

As you are writing, be sure to integrate your figures into the text you are writing so that it is clear why you have included them.

A lack of clear and sufficient data can completely derail a grant application. It is worth spending considerable time making sure your data are correct, understandable, and sufficient to establish feasibility of the experiments you are proposing.