Periodicity in cardiac admissions to A&E+

Additional slides for paid subscribers

I have been wondering what post to make to kick off the paywall series and my mind keeps wandering back to the strange, wave-like behaviour of cardiac admissions to A&E that we observed in previous posts. This ebb and flow wasn’t seasonal (more cases during winter) and seemed to have a periodic structure. I decided to utilise the CDS daily dataset spanning the period 1st November 2017 – 18th September 2021, this giving us 1,722 data points to play with. Counts of daily admissions were derived for those under 45 years of age and those aged 45 years and older in keeping with previous analyses; these two time series were run through a statistical technique called spectral analysis.

Spectral analysis is a method for determining if there are cyclical patterns in time-based data. For example, there is a strong weekly pattern to all elective surgery and we expect this to have a frequency of λ = 0.1429 within a daily time series. In case folk are wondering how on earth we arrive at this weird …