Abstract
The world is rapidly changing, and the systemic shifts have the potential to affect the nature of work. To prepare the workforce, it is crucial to develop the skills that will be necessary for the unpredictable landscape of the future. Before these skills can be developed, however, they have to be identified and quantified through some form of valuation. It is important that the approach to skills valuation is empirically defensible. This article presents an approach to skills valuation that focuses on the extent to which a skill facilitates occupational transitions as its measure of value. This valuation metric is then developed using a graph-theoretic approach. Results show that this valuation reflects skills-importance that aligns with existing skills valuation in the literature. Limitations of this approach and its potential extensions are discussed.
Keywords
Background
Studies that look at recent and predicted changes in the jobs landscape have consistently shown that disruptive changes are coming—ranging from a shift in skillsets that can adapt to changing work environments and demographics, to potential industry-level disruptions due to large-scale adoption of technology (such as artificial intelligence [AI], deep machine learning, and automation/robotics). In particular, the Future of Jobs Report published by the World Economic Forum (WEF, 2016) suggests that skills that are increasingly going to be important in the next 5 to 10 years will almost exclusively be those classified as “21st century skills” by various frameworks (e.g., Dede, 2010; Organisation for Economic Co-operation and Development [OECD], 2008; Partnership for 21st Century Skills, 2009; United Nations Educational, Scientific and Cultural Organization [UNESCO], 2015). The term “21st century skills” (21CS, also called transferable/transversal or cross-functional/cross-cutting skills) is an umbrella term that encompasses a broad range of skill sets and competencies, such as critical thinking and problem-solving skills, that are deemed important in the current century (Ercikan & Oliveri, 2016; Rotherham & Willingham, 2010). These skills continue to gain attention and importance in the current and future educational environment, and yet education systems are
Although there is consensus across all sectors that these 21CS are important, there are serious logistical considerations that need to be taken into account before a systems-level adoption can be formalized. As an umbrella term, 21CS encompasses a very broad set that, depending on the framework, can include over two dozen distinct skills (e.g., National Center for O*NET Development, 2019a; UNESCO, 2015). Teaching any one skill to an entire student population requires substantial educational expenditure. If countries decide to embed these to their curriculum, the selection of which ones to focus on has to have empirical support based on some quantifiable metric of “value.”
The first step toward systems-level adoption and formalization of these skills is to
Survey methods show what skills are needed now (current demand) or what the survey respondents think will be needed in the foreseeable future (
If we are to project future demands and priorities, we have to focus on flexible and transferable skills. Although this will still be limited because we cannot predict what future occupations the skills
This article aims to complement the approaches described above and demonstrates a method that aims to provide quantitative data on what skills are required now as students transition into the workforce, and what skills will allow them to be more flexible in the fast-changing work environments in the next decade. To do this, the method introduced in this article involves the development of a
We quantify this valuation using a networks-based skills metric that is a ratio-level measure (i.e., an interval scale with a meaningful zero value, thus allowing for meaningful comparisons of ratios). This ratio-level measure of
Concept
The idea of the “transferability-valuation” of skills metric is based on the concept of network connections where the transition from one state to the next is viewed as a “path” between two nodes. The nodes represent the states (a “state” in this case is a job or occupation), and the path is represented by a line that connects them. In Figure 1, the transition from being a recent graduate entering the workforce is represented by various paths for each potential job target.

Visualization of transition from a recent graduate to various engineering jobs.
In each of these potential transitions, the relevant skills that help make a transition possible can also be modeled as a node that sits between each occupational transition (e.g., the three skills in Figure 2). Because some skills may be more important that others depending on the situation, the mapping can also incorporate the extent to which each skill contributes to the transition. For example, Figure 2 visualizes the different

Visualization of various skills required, and their respective levels of contribution, in the transition from one job to another.
All the “paths” within a given context (e.g., for a given field of occupation, for a country, or for an industry) can then be built into a network that models all transitions, not just for new graduates but also for those transitioning between jobs (see Figure 3) and include all the skills involved in each transition. Finally, each transition can be mapped separately by using directional paths. That is, a transition from job A to B is modeled as separate from a transition from B to A. This also allows the network to specify

Visualization of a network representing multiple transitions and multiple skills required for each transition.
Method
Data
Occupation data and linked skills were extracted from the O*Net version 23.2 Database (National Center for O*NET Development, 2019b). The O*Net database contains regularly updated information on nearly a thousand detailed occupations in the United States, categorized into 23 major occupation groups, structured according to the 2018 Standard Occupational Classification (SOC; U.S. Bureau of Labor Statistics, 2018).
The SOC structure classifies all occupations in the United States and categorizes the occupations under hierarchical levels of aggregation (see U.S. Bureau of Labor Statistics, 2018). For this article, Architecture and Engineering Occupations (hereafter referred to as the AEO group) was chosen as a major group (SOC category 17-XXXX) in the main analysis. Under this broad category, 70 detailed occupations were included. For a parallel analysis, two additional data sets were constructed: The Social Sciences Occupations (SSO group; SOC category 19-30XX) with 16 detailed occupations included in this category, and the Production Occupations (PO group; SOC category 51-XXXX) with 96 detailed occupations. The SOC has an intermediate and higher-level aggregations. The two data sets for the parallel analysis were chosen such that SSO is aggregated with the AEO occupation group for the main analysis (both are in an intermediate aggregation of Computer, Engineering, and Science Occupations), whereas PO is aggregated separately in both the intermediate and higher-level aggregations (see Tables 5–6 in U.S. Bureau of Labor Statistics, 2018).
The set of skills included in the analysis were taken from the list of skills and abilities from O*Net data. As the relevant skill set depends on occupation, one of the skills for the AEO group,
For the first analysis, there were 16,848 pairwise permutations of 70 AEOs across 10 skills. These permutations represent all possible pairwise occupational transitions that are modeled as basis for the main network analysis.
Table 1 shows a sample of 10 pairwise permutations (out of 16,848). Each row shows a transition from one occupation to another, across all the 10 skills for the AEO group. These transition pathways are filtered to exclude those where the rated importance of the skill for either the source and target occupations is less than 3 on a 1 to 5 scale defined by O*Net as 1 =
All Pairwise Permutations of Occupational Transitions for the AEO Group.
This has the effect of filtering pathways that involve less important skills for any particular transition. All occupations in the PO group have an importance value on
The idea is that for any given path, the transition from an occupation that places greater importance on a particular skill to another occupation that places less importance on that skill will be comparatively easier than the other way around because little or no upskilling will be needed. This weight is then scaled so that the minimum weight is 1. This is visualized in Figure 4 using as an example the transition from Mechatronics Engineer to an Energy Engineer shown in the first three rows of Table 1. In the network analysis, this weight acts as an edge weight and contributes to the occupation pair’s link strength in the context of a weighted network (Opsahl et al., 2010).

Visualization of a specific transition, where path thickness represents edge weight in a weighted network.
For the second analysis, there were 1,346 pairwise permutations of 16 SSOs across 10 skills and 10,404 pairwise permutations of 96 POs across nine skills. This analysis was done in parallel with the data kept separate because we are interested in transitions exclusively within the broad occupation groups. Research suggests that transitions are more likely for similar occupations (WEF, 2018). It is possible, and indeed has been observed, that workers transition from being an engineer to a sociologist but it is not common.
There is also a technical purpose for computing the centrality metrics for each of the occupational groups separately. Had the data been combined, the interpretation of the betweenness values would be confounded by the characteristics of the particular occupational networks. If one network has stronger characteristics, such as having more centralized nodes and stronger links among its nodes, the ranking of the betweenness metric in such a combined data set would be overrepresentative of that network. However, the more important substantive purpose of the second parallel analysis is to show differences in skill centrality within specific domains while also informing which skills may be cross-cutting by being central in more than one domain even if the computation of the centrality metrics was done independently.
Analytical Approach
As discussed in the “Concept” section, the combined possible paths that individuals can take as they move from one occupation to another can be modeled as a network where occupations are represented as nodes or vertices and the transition represented as edges in a directed graph. A directed graph is simply one where the connections (or edges) specify a direction. Directional paths are important for our purposes because they model the temporal order of the transition—the transition
where σ
The distance between node pairs that are directly connected (i.e., the pairs are adjacent, with no intervening node/s) is set to 1, and the shortest path between any node pair (
where
To enable the computation of betweenness centrality for the skills, every skill that is relevant in a transition is modeled as a node that always sits between the two transitioning occupations (see, for example, Figure 2). A skill node with a betweenness metric value of 0 therefore means that no shortest path passes through it, implying that the skill is not important for all transitions in the network. The metric is then normalized such that the range of values is scaled to
To illustrate how betweenness centrality is computed in a simple undirected graph, Vertices 2 and 4 in Figure 5 have the following (non-normalized) centrality values:
Betweenness for
Node pair (1,4): σ1,4 = 2, σ1,4(2) = 1
Node pair (1,5): σ1,5 = 2, σ1,5(2) = 1
Node pair (1,6): σ1,6 = 2, σ1,6(2) = 1
Betweenness for
Node pair (2,5): σ2,5 = 1, σ2,5(4) = 1
Node pair (3,5): σ3,5 = 1, σ3,5(4) = 1
Node pair (1,5): σ1,5 = 2, σ1,5(4) = 2
Node pair (1,6): σ1,6 = 2, σ1,6(4) = 2
Node pair (2,6): σ2,6 = 1, σ2,6(4) = 1
Node pair (3,6): σ3,6 = 1, σ3,6(4) = 1
Node pair (5,6): σ5,6 = 1, σ5,6(4) = 1

Sample network.
In an
Because we are using a
The details of the algorithm for computing betweenness centrality in weighted networks is beyond the scope of this article (for more details, see Brandes, 2001; Opsahl et al., 2010), but the effect of the weights on networks is that the distance between strongly connected nodes (i.e., where the weights are greater) becomes comparatively shorter and thereby lessening the “cost” of traversing such path (Brandes, 2008).
The substantive implication, for the purposes of this article, is that the paths with lower costs of traversing effectively increase the betweenness centrality of nodes that these paths pass through. Using Figure 4 as an example,
All data preparation and analyses were conducted within the R environment (R Core Team, 2018). The
Results
The results show that the top skills based on their betweenness centrality reflect what would be generally considered important skills for the particular group of occupations (Tables 2–4). However, the results provide information beyond “importance.” Because the betweenness centrality metric is a
Ranked Betweenness Centrality for the AEO Group.
Ranked Betweenness Centrality for the SSO Group.
Ranked Betweenness Centrality for the PO Group.
The metric is a ratio therefore magnitudes are directly comparable within each occupation group (e.g.,
Comparison of Skill Rankings Across Broad Occupation Groups.
Skills that are conventionally associated to an occupation group also tend to be the most central skill and have rankings that are different from the other occupation groups. It is expected that engineers need good
Table 5 also shows the commonalities across the WEF and Burning Glass/BHEF reports. Both reports provide a metric for “value” that is different from the metric based on betweenness centrality; thus, the commonality across the rankings based on both metrics offers additional support for a more universal interpretation of “value” for some skills such as
Discussion
There is a long history of work in the literature on how systemic shifts affect skills valuation in terms of industry demand or occupational requirements (Acemoglu, 1998; Berman et al., 1998; Bughin et al., 2018; Levy & Murnane, 2005). As a consequence, those in the educational community have realized the importance of preparing the future workforce and are developing internationally accepted frameworks that drive toward a consensus on a handful of skills that are deemed key to the future (Dede, 2010; Rychen & Salganik, 2003). Empirically defensible skills valuation is therefore of critical importance. This article investigates this valuation of skills using a large-scale data-driven approach. Our results show that an alternative interpretation of value can be defined as facilitating transitions in an unpredictable landscape. This interpretation yields a “transferability-valuation” of skills that focus on quantifying the smoothest/best transition between the most number of occupation pairs.
We discuss the results by first comparing this type of valuation with those based on broad opinion-based approaches. Table 5 shows that there is close alignment with our approach and the finding from WEF (2016) and Burning Glass/BHEF, even if both the WEF and Burning Glass/BHEF reports aggregate the skills over a broad field. This shows that certain skills—
Looking more closely within occupation groups, results show that skill valuation depends on the characteristics of the field linked with each occupation group. This finding is highlighted by the differences in ranking for skills that are contextually linked to each occupation group in the analysis—thus
Cross-cutting skills lose a bit of their advantage when the transition is constrained within a field. For example, both
The only skill that is both cross-cutting and has very high “transferability-value” within every occupation group is
An advantage of using a ratio-level centrality metric is that the cross-cutting characteristic of each skill can be examined in more detail. While the rankings show that
This article’s data-driven approach to skills valuation can be useful in both occupation-specific and higher-level contexts, enabling a more comprehensive quantification of skills value beyond rankings. A large-scale workforce skills survey by the McKinsey Global Institute found that one of the main concerns of business leaders is that their workers may not be adaptable enough and hampering retraining and redeployment as firms build their workforce of the future (Bughin et al., 2018). Specific industries can apply this approach toward targeted and efficient allocation of resources for re-skilling or upskilling within their scope (e.g., as discussed in WEF, 2018) by helping identify which skills are most transferable within specific industry or even firm-level contexts. Provided the underlying data exist, the approach can be made as specific/localized as possible and applied to any contexts (e.g., occupational groups, industry, geographic area, demographic category) as well as multiple contexts simultaneously. At a higher level, decision makers can adopt this approach to inform evidence-based policies on preparing the future workforce across the entire system.
Extensions to Future Work and Limitations
In a graph-theoretic framework, there are centrality metrics that focus more on the frequency of connections regardless of whether these connections facilitate links to as much of the rest of the network as possible. These centrality metrics are
More sophisticated metrics such as the
Future work based on similar graph-theoretic approaches will share the same limitations of this current work. The robustness of the findings is inherently linked with the extent to which the raw data from O*Net and the methodology of the underlying the data collection process are also robust. There is no reason to doubt the quality of O*Net data, given that both the data sets and methodologies have extensive history of research over the years. The skills and their importance were classified and rated subjectively, but the rating process was systematic and involves highly trained analysts with domain expertise (see National Center for O*NET Development, 2012). Nevertheless, the assignment of skills to occupations and the rating of importance have direct impact on the results of this analysis and thus constitute a limitation of this article.
It would be of interest to the research community if this approach is replicated using other SOC schemes, although it might be a challenge to find national-level data sets that are as comprehensive as O*Net. For example, the United Kingdom SOC (Office for National Statistics, 2010) only has corresponding skill
Footnotes
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
