Use of 'this', 'these' and 'such' + a noun

An effective way to create flow in your text is to refer back to nouns and ideas using a determiner + a noun. This strategy is especially useful at the beginning of sentences – just like in this sentence! – since it will help you move from given to new information . In examples (1) and (2), the phrases in bold refer back to [the information in square brackets] in the previous sentence. 

(1)

For instance, every day [the earth is provided with an enormous amount of solar energy when photons reach the surface of the planet]. This process contributes with 4·10²⁴ J yearly, a generous supply of renewable energy ready to be harvested.

(2)

However, to guarantee stability, [the cost function should have an infinite time horizon, T=∞]. This requirement causes some issues since it is very difficult, if not impossible, to solve such an optimization problem for nonlinear systems.

The words this/these can be used alone to refer back to given information, but they are often followed by a summary noun phrase to increase precision. If you remove process from example (1), and requirement from example (2), the meaning is less precise.

Research (Drummond, 2016) suggests common summary nouns in academic writing include:

time, case, point, view, period, process, approach, question, problem, area

Consistent use of summary nouns

When using summary nouns, consistency can help the reader to navigate the text. In example (3a), the writer uses several different summary nouns, ‘way’, ‘approach’ and ‘method’, when referring back to the same thing. Some readers may wonder if three these different nouns refer to three different things. In (3b), the summary noun ‘method’ is used consistently, removing any ambiguity.

(3a)

There are two distinct ways in which anatomical MR images can be combined with PET data. The first approach involves utilizing MR imaging to identify anatomical regions of interest (ROIs), which are then used for analyzing PET data. Alternatively, the second method involves leveraging aspects of the MR image to directly impact the reconstruction of the PET image.

(3b)

There are two methods for combining anatomical MR images with PET data. The first method involves using MR imaging to identify anatomical regions of interest (ROIs), which are then utilized for analyzing PET data. The second method leverages aspects of the MR image to directly influence the reconstruction of the PET image. This method is based on the understanding that PET images, whether they depict metabolism, blood volume, or receptor binding, inherently display spatial patterns that mirror the underlying anatomy.

Simple and complex summary noun phrases

Summary noun phrases may be simple or complex, with the determiner (e.g. this) being followed by a single noun (e.g. process), or a longer phrase (e.g. this complex process). The latter often increases precision. Example (4) includes two precise summary noun phrases in bold. The phrases they refer back to are set within square brackets.

(4)

The emission of greenhouse gases (GHG) is the primary driver for global warming and the effects that this has on climate change. Cities play a significant role in this problem as they are responsible for 70% of global CO2eq emissions [1] [2]. Therefore, there is great potential to reduce GHG emissions by introducing [innovative technologies] in urban environments. One promising technology is [Photovoltaics (PV) coupled with energy storage systems (ESS)]. This combination of technologies enables electricity generation and controlled utilization in urban environments.

Signalling writer attitude

The choice of summary noun can signal criticality. In fact, Flowerdew (2003) calls summary nouns ’signalling nouns’, as they can signal writer attitude.

(5)

[The market is intricate and unpredictable.] This challenge presents an opportunity for Machine Learning (ML) to develop a model that can forecast future prices based on historical datasets.

(6)

[The product demands are subject to several volume constraints.] This problem has been tackled previously by limiting the distribution of demand.

Note the contrast between challenge in example (5) (viewed positively by the writer) and problem in example (6) (viewed negatively by the writer). Words such as adjectives can be added to enhance this effect, e.g. this serious problem vs. this minor problem.

Should I use 'this' or 'that'?

In general, you should write this or these. This, these, and such are more suitable determiners for creating information flow than that and those, though the latter two do sometimes occur.

References

Drummond, A. (2016). An investigation of noun frequencies in cohesive nominal groups. Journal of Second Language Teaching and Research, 5(1), 62–88.

Flowerdew, J. (2003). Signalling nouns in discourse. English for Specific Purposes, 22(4), 329–46.

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