Linking as-clauses

A common structure for introducing informative statements is the linking as-clause. Here are three examples.

As shown in Fig. 1 and Fig. 2, the companies used in this survey varied significantly in geographical location, size, and method of operation.

As can be seen in Table 5, the overall rate of recall, while low, also showed considerable variation.

Shallow junction GM APDs, peripheral area test structures, and gate-controlled diodes, as show in Figs 1(a), 1(b), 1(c), were manufactured in p-type epitaxially grown bulk silicon using a conventional 1.5 µm CMOS process reported previously.

These linking clauses (where as does not equal since or because) are exceptional in English grammar. In the passive, these linking clauses have no subjects. Compare the following sentences:

a. As it has been proved, the theory may have practical importance.

b. As has been proved, the theory may have practical importance.

In sentence a there is a causal relationship between the as-clause and the main clause. Because the theory has been proved, it may have practical importance. In sentence b the as-clause serves to suggest that the practical importance of the theory (not just the theory) has been established. Although you may find examples that run contrary to this advice, remember, then, not to use subjects in passive linking as-clauses.

Finally, using prepositions with this type of linking statement can be tricky. Here are some of the main standard uses.

in           As shown in Table 1...

by          As predicted by the model...

on          As described on the previous page...