What importance, if any, does time series have and how will it be relevant in the future? These are just a couple of fundamental questions that any user should find answers to before delving further into the subject. Let's try to answer this by posing a question. Have you heard the terms big data, artificial intelligence (AI), and machine learning (ML)?
These three terms make learning time series analysis relevant. Big data is primarily about a large amount of data that may be analyzed computationally to reveal patterns, trends, and associations, especially relating to human behavior and interaction. AI is a kind of technology that is being developed by data scientists, computational experts, and others to enable processes to become more intelligent, while ML is an enabler that is helping to implement AI. All three of these terms are interlinked with the data they use, and a lot of this data is time series in its nature. This could be either financial transaction data, the behavior pattern of individuals during various parts of the day, or related to life events that we might experience. An effective mechanism that enables us to capture the data, store it, analyze it, and then build algorithms to predict transactions, behavior (and life events, in this instance) will depend on how big data is utilized and how AI and MI are leveraged.
A common perception in the industry is that time series data is used for forecasting only. In practice, time series data is used for:
- Pattern recognition
- Forecasting
- Benchmarking
- Evaluating the influence of a single factor on the time series
- Quality control
For example, a retailer may identify a pattern in clothing sales every time it gets a celebrity endorsement, or an analyst may decide to use car sales volume data from 2012 to 2017 to set a selling benchmark in units. An analyst might also build a model to quantify the effect of Lehman's crash at the height of the 2008 financial crisis in pushing up the price of gold. Variance in the success of treatments across time periods can also be used to highlight a problem, the tracking of which may enable a hospital to take remedial measures. These are just some of the examples that showcase how time series analysis isn't limited to just forecasting. In this chapter, we will review how the financial industry and others use forecasting, discuss what a good and a bad forecast is, and hope to understand the characteristics of time series data and its associated problems.