During the development of an organism, it is important for the cell to know its position in the embryo, to differentiate into an appropriate cell type. The concept of ‘morphogen gradient’ was proposed to realize this requirement. In this concept, morphogen is secreted from source cells and diffuses to form a gradient of concentration in the embryo. Depending on the difference in the concentration of the morphogen, the receiver cells know the distance from the source, and differentiate into appropriate cell types. For this model to function accurately, the biological noise must be low enough, i.e. the production, diffusion, and recognition of the morphogen must be accurate enough. The noise and accuracy of the morphogen gradient had not been quantitatively evaluated before this paper.
This paper combines quantitative imaging and statistical analyses. The latter might be difficult to follow. In that case, just skip the details and try to follow the main logic of the paper.
For further reading, I recommend you to check the accompanying paper by the same group (Gregor et al., Cell 130, 141-152 (2007).)