Figure 5.
The three-panel image illustrates time series analysis of keyword usage over time. The x-axis shows Year and the y-axis shows Annual Frequency. The top panel presents the hot keyword Signal, with observed values increasing gradually from the early 1990s to recent years, followed by a forecast using Autoregressive Integrated Moving Average model 2 with 95 percent and 80 percent confidence intervals. The middle panel shows the active keyword Track, where values fluctuate, decline around 2010, then increase again, with forecasts generated using Autoregressive Integrated Moving Average model 1 and associated confidence intervals. The bottom panel presents the cold keyword Test, showing a general downward trend in annual frequency over time, with a relatively flat forecast and uncertainty bands extending into future years.Predicting promising patent keywords through optimal ARIMA models with confidence intervals