In the early 1990’s as data mining was evolving from toddler to adolescent, we spent a lot of time getting the data ready for the fairly limited tools and computing power. As the 90’s progressed, the need to standardize the lessons learned into a common methodology became increasingly acute. Two of leading tool providers of the day – SPSS and Teradata – along with three early adopter user corporations, Daimler, NCR, and OHRA convened a Special Interest Group (SIG) in 1996 and over the course of less than a year managed to codify what is still today the CRISP-DM, CRoss Industry Standard Process for Data Mining. CRISP-DM was not actually the first. SAS Institute had its own version called SEMMA (Sample, Explore, Modify, Model, Assess). Nevertheless, within just a year or two many more practitioners were basing their approach on CRISP-DM.
The CRISP-DM process or methodology of CRISP-DM is described in these six major steps:
- Business Understanding: Focuses on understanding the project objectives and requirements from a business perspective, and then converting this knowledge into a data mining problem definition and a preliminary plan.
- Data Understanding: Starts with an initial data collection and proceeds with activities in order to get familiar with the data, to identify data quality problems, to discover first insights into the data, or to detect interesting subsets to form hypotheses for hidden information.
- Data Preparation: The data preparation phase covers all activities to construct the final dataset from the initial raw data.
- Modeling: Modeling techniques are selected and applied. Since some techniques like neural nets have specific requirements regarding the form of the data, there can be a loop back here to data prep.
- Evaluation: Once one or more models have been built that appear to have high quality based on whichever loss functions have been selected, these need to be tested to ensure they generalize against unseen data and that all key business issues have been sufficiently considered. The end result is the selection of the champion model(s).
- Deployment: Generally this will mean deploying a code representation of the model into an operating system to score or categorize new unseen data as it arises and to create a mechanism for the use of that new information in the solution of the original business problem. Importantly, the code representation must also include all the data prep steps leading up to modeling so that the model will treat new raw data in the same manner as during model development.
I believe CRISP-DM’s longevity in a rapidly changing area stems from a number of characteristics:
- It encourages data miners to focus on business goals, so as to ensure that project outputs provide tangible benefits to the organization. Too often, analysts can lose sight of the ultimate business purpose of their analysis – the analysis can become an end in itself rather than a means to an end. The CRISP-DM approach helps ensure that the business goals remain at the centre of the project throughout.
- CRISP-DM provides an iterative approach, including frequent opportunities to evaluate the progress of the project against its original objectives. This helps minimize risk of getting to the end of the project and finding that the business objectives have not really been addressed. It also means that the project can be adapted and changed in the light of new findings once it’s up and running, rather than being static.
- The CRISP-DM methodology is both technology and problem-neutral. You can use any software you like for your analysis and apply it to any data mining problem you want to. Whatever the nature of your data mining project, CRISP-DM will still provide you with a framework with enough structure to be useful.
From today’s data science perspective this seems like common sense. Data science has moved beyond predictive modeling into recommenders, text, image, and language processing, deep learning, AI, and other project types that may appear to be more non-linear. If fact, all of these projects start with business understanding. All these projects start with data that must be gathered, explored, and prepped in some way. All these projects apply a set of data science algorithms to the problem. And all these projects need to be evaluated for their ability to generalize in the real world. So yes, CRISP-DM provides strong guidance for even the most advanced of today’s data science activities.
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|2.||↑||Wirth, R & Hipp, Jochen. (2000). CRISP-DM: Towards a standard process model for data mining. Proceedings of the 4th International Conference on the Practical Applications of Knowledge Discovery and Data Mining.|