Some comments on the Ocean Glider paper

To call it a new paper might be a little bit extragated, but its publication happend within the last year. Actually it was submitted around a year ago and published online in November, but the actual publication of the paper happend in April. The name is quite long, but tells you already a lot of its content:

Turbulence and Mixing by Internal Waves In The Celtic Sea Determined From Ocean Glider Microstructure Measurements

I do not want to talk about the whole paper, as my personal contribution was tiny compared to the great work of the other authors. Anyway, I would like to write a little bit about my part in it and what the task was.

Ocean gliders are one of the relatively new tools, which currently revolutionise the oceanographic observation system. As such they are currently tested for many applications, in case of this article for microstructure measurements. My part therein started when the main work was already done. After all the measuring, processing and calculations two time series over nearly nine days were given to me with the simple question: “What can you tell us about them.” Of course there were ideas around what could be in it, but as I do statistics, it is my task to make statements waterproof.

As always, you have to get familiar with the data in the first place before you can investigate detailed questions. I did quality assurance science during my PhD and from this I have my standard tools to play around with data and to learn about it. One of these tools is the histogram test, which is a nice test on inhomegeneities within datasets. The first thing you find with it is that there are obvious cycles within the time series, so you ask the experts to give you the obvious and physical most probable cycles you might find therin. Of course you can also tell exactly, which cycles have to be in it, by performing a spectral analysis, but when you make decsisions on simplifying and clustering data, it is better you understand the physics behind it. After doing this it was obvious that there are two different parts of the dataset (with different statistical properties), which are on the first view quite unrelated. The information to look at the data in the logarithmic sense, was then the main driver for the upcoming analysis.

When you assume distributions of the data it is important to test them. Done this it was simple to show that the time series are indeed, apart from the extremes, log-normal distributed. Performing the histogram test again, now with the logarithmic data, showed still the regime shift as before and so it was now the interesting question, whether the two parts itself were also log-normal distributed. Using qq-plots it was simple to show that they were and that just the mean and standard deviation in the logarithmic sense have changed. So my part got to an end, it was written up as one section at the end of the paper and I was happy with it.

So why are such analyses important? Why bringing in additional statistics into such a paper, while it is already a solid one? Because these small simple analysis contribute to the overall understandings of the data. Knowing the distribution of data values and its changes over time helps in modelling them or understanding the physics. Giving people simple tools at hand to see inhomogeneities would also allow for real time testing the data and might open new ways of measureing them. And yes, it gives nice figures, which illustrate the reader that there is really something within the data that might need further exploration. Statistics is not all about the equations, sometimes the right visualisation is equally important. All in all it was a nice example, how domain experts and their methodologies and a simple statistical analysis give quick and solid results.


M.R. Palmer, G.R. Stephenson, M.E. Inall, C. Balfour, A. Düsterhus, J.A.M. Green (2015): Turbulence and mixing by internal waves in the Celtic Sea determined from ocean glider microstructure measurements. Journal of Marine Systems, 144, 57-69

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Application processes in science

In the past months the blog was quite calm, and so often when scientific blogs get deserted, it has something to do with the job of the author. This was also the case here (apart from the election censorship in the UK) and so the time usually used for writing a post was required to write applications, prepare and attend job interviews and moving to the new position. Usually scientists do not talk much about this topic, as it is of cause highly sensitive. Nevertheless, I had written in the entry statement of this blog that I want to give insight into the job of a scientist. And without doubt, working on fix-term contracts and switching to a new position is an essential part of the job of an early career scientist. But don’t worry, I will keep it very general and will just make some statements on how the general process works and some problems, which can be encountered by the scientists.

So most contracts in geoscience (so when you look up the job description sites) for post-docs have a length in a range of 2 to 5 years. In some cases it is possible to extend, but in general it has to be assumed that after the time is up, the money is up. Depending on the country and their social systems that can really be a problem, so that it is essential to find a new job before the contract ends. Unfortunately, in short term contracts this coincide with the time the final papers are written, which makes it for some a special case of multi-tasking. As a consequence, several month before the end of a contract the scientist have to look for his future. It can be even earlier, when certain deadlines for future perspectives are on the wish-list, e.g. fellowships or writing a proposal.

A major thought process in the application phase is the decisions for which jobs someone wants to apply for. Generally, there are two dimensions which dominate the process (at least in my theory). The first is the location. This can be the continent, country or the type of the institution (university or research institution). The other dimension is the research topic. Of cause there exist also a dimension on the level of the position, but that is something that I would like to count to the location dimension. With these two dimensions, it is like the uncertainty principle. When one is constraint due to personal decision (e. g. due to family/relationship or the best fitting topic for the future research path), the other one will widen.

After deciding on the jobs you want to apply for, a similar process starts for every position. Working through the job descriptions, writing cover letter and fighting through the application process. Many institutions build nowadays their own web environment, and the more compelex they are the more problems they bring. Of cause they force you to think about, whether you want to apply at all, but in the phase where you usually apply for a job, you anyway get picky about those you want to apply for (simply because of time constraints). These systems might make sense for the institutions, but definitely not for the applicants. In a few cases there is still the option to send the cover letter and cv directly via mail, which is definitely, from the applicants point of view the best solution.

Having done that, the time of waiting starts and this teaches one a lot about the potential future employer. Some institutions react quick, inform the applicants in a lot of detail of the process, whether they are short listed or not. This can happen in a week, which is great for all involved. Nevertheless, there are institutions who need a month to reply and some are not replying at all. I do not want to comment on that, but as I said, it tells you a lot about the institutions.

Being lucky and getting invited to the interviews is usually the first part of the process, from which the applicant benefits. Be it in a video-interview or taking part in person, it is a great chance to get to know the potential future employer. Whether you get the job or not is therein secondary (at least in this moment), because you still learn something from this time. Preferences on the methodology of the interview depend on each individual, both have their advantages and disadvantages. Nothing can replace real contact, but sometimes it is better for everyone, when some details are hidden behind a screen.

From then on begins the wait, which is in the most cases quite short. Many panels decide within hours on their preferred candidate, and s/he will be the only one who gets informed. For the others it is usually a long wait, until the people ranked above them have declined or accepted the position.

All in all, the application phase within a job are exciting times, the problem is only that it costs a lot of time and effort, while you do not have any of them to spare. So in the end I am happy that this phase found an end for me, but I am well aware, that it waits just around the corner, again at a time, when it is certainly not fitting into my current job.