# Integrating Sustainable Performance into the Digital Maturity Models for SMEs in Manufacturing
## 3 Literature Review
### Sustainable Performance Measurement
#### 3.3.1 Economic Performance  
Economic indicators are the most used in the literature to measure business success. Of the 28 articles collected, 24 use at least one economic dependent variable to measure economic performance. This section provides a detailed overview of all economic indicators identified in the literature to deepen knowledge on sustainable performance indicators. The following is divided into three main categories: **classic financial indicators**, **continuous improvement**, and **competitive advantage**. First, most authors suggest classic financial indicators related to **fixed production costs**, **cash reserves**, **investments**, and **available working capital** to measure economic performance. Indeed, it seems logical to use classic financial indicators to achieve profitability goals. Eighteen authors suggest using **production costs** as a measure of project benefits, with 15 of these 18 authors, including [46, 47], using production **cost reduction** as a primary profitability indicator. Some authors also use more specific terms. For example, refs. [34, 48] introduce measurements for **water and electricity consumption costs**, **inventory costs**, and **raw material costs** to break down production costs in greater detail. Other authors, like [49], suggest that eliminating time losses in production can result in financial gains such as reduced labour costs. For this reason, they use production **time savings** as an indicator affecting production costs. Most studies using these indicators show that I4.0 has had a positive impact on reducing production costs. However, the opposite can also be true. Ref. [50] suggests that DT can have a negative impact on production costs. Their results show that additional fixed costs may arise, especially when a company relies on external resources for a digital project. They include **external assistance costs**, among others, as an indicator in their article. Unlike production costs, several authors also mention **cash inflows** as an indicator for measuring economic performance. Refs. [51, 52] use measures like **ROI** to assess cash benefits in business studies. Ref. [53] and ref. [50], respectively, use **profits** and **revenues** (selling price) to evaluate these benefits. Additionally, ref. [54] reports in their articles that increased **sales forecasts**, resulting in future revenue growth, also contribute to measuring economic performance related to cash inflows [44]. Moreover, unlike the production costs mentioned by [50], the authors also suggest measuring the **percentage of external financial** assistance, such as government grant programs [53]. In addition to cash inflows and outflows, refs. [44, 49] suggest measuring the **level of working capital** to quantify the **capital available for investment**. To operationalisethis measure, as done by [55; 56], some authors use indicators such as the **percentage of investment in research and development (R&D)**, the **percentage of investment in technological infrastructure**, and the **percentage of investment in I4.0-related projects**. These measures somewhat represent the company's profits reinvested during the year. However, ref. [56] suggests not limiting measurement to the percentage of reinvested funds but also considering the **percentage of unused financial** capacity to fully gauge economic performance. Secondly, a large part of the literature also notes that process improvement is closely linked to economic performance. For this reason, several authors also suggest measuring the **level of continuous improvement** through the **efficiency of operational and informational processes**[56; 57]. Eighteen out of 28 articles discuss the importance of measuring these variables to understand the overall economic impact of a project. In the articles included in this literature review, such as those by [47; 52; 58], the primary indicator used to measure a factory's operational efficiency is the **Overall Equipment Effectiveness (OEE)**. In their article, ref.