02 June 2017 User Stories

Kibana baby kick counter - part 2

By Barnaby Gray

This is part 2 of 2 about using Elasticsearch and Kibana to track patterns in baby activity. Part 1 here covers the hardware and setup for tracking baby kicks.

Machine learning

Having collected about 6 weeks of baby kicking data, it's time to test the new toy in the Elastic Stack: Machine learning. Machine learning is a feature of X-Pack -- which you can test out using a 30-day trial license -- and installing it was a straightforward case of following the instructions. From the new 'Machine Learning' app in Kibana, I chose 'Create new job', and 'Create a single metric job':

image1.png

Pointing it towards my index, choosing aggregation 'Count' and then Create Job and you get a nice preview of the analysis scanning through the data and highlighting anomalies as it goes:   

bumps 30min (1).png


Once this is complete you can open up the Anomaly Explorer and run through events that it has identified as anomalous:

bump 30m 2 (1).png


It has detected that 12 kicks at 12am are unusual where no activity would be expected, and identified this purely from the implicit patterns without needing to be trained what to expect (ie. unsupervised machine learning) - neat!

I did some reading up on the medical advice for expectant mothers monitoring baby activity, which as often is the case is a bit mixed depending on what you read. It used to be a simple rule of thumb: time how long it takes for 10 kicks to be felt (so called 'count to 10') and if this is within 2 hours, everything is fine. Apparently this is a bit of a broad generalisation and activity varies quite widely from baby to baby. What's emphasised now is it's important to spot changes in the normal pattern of activity for your particular baby - all babies being different.

We wanted to spot the situation where activity drops from normal, which could be indicative of a problem. So I created another job with aggregation type 'Low count' of these anomalies.

None were identified in our data - phew! :-)

And just to test this theory I wanted to remove a period of data and see whether the anomaly detection would pick up this simulated drop in activity. To do this I could have manually deleted data, but instead I used the powerful and underrated index aliases feature to create an alias to my original data limited by a query excluding a gap of time on 1st May:

echo '{
     "actions" : [
         {
             "add" : {
                  "index" : "bumps",
                  "alias" : "bumpless",
                  "filter": {
                      "bool": {
                          "must_not": {
                              "range": {"timestamp": {"gte": "2017-05-01T01:15:00", "lt": "2017-05-02"}}
                          }
                      }
                  }
             }
         }
     ]
  }' | curl -XPOST -u elastic:changeme localhost:9200/_aliases

And finally, running the same low count job on this flagged this period as 41x lower. Great - simulated anomaly correctly identified.

  image4.png

In conclusion

This simple example illustrates the machine learning module has great potential application in the field of health monitoring (with suitable caveats - I am not a doctor, etc!).


author-barnaby-gray

Barnaby Gray studied Computer Science at the University of Cambridge, before working at various search focussed companies and start-ups. He currently works on data science at Realla, a London based proptech startup, and is looking forward to meeting the baby!