15, 18, 21, 12, 19
Generate a prediction for the following time series data.
Based on the limited information provided, it is not possible to predict the next value of the time series with certainty since the given data does not present a discernible pattern or trend. However, considering the increased data points and assuming a linear trend, I estimate that the next value could be around 20 +/- 3.3, where 3.3 is roughly the standard deviation of the given data.