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Feb 6, 2014

Improving Your Fly-Fishing Odds – with JMP

Most of us who brave Midwest winters pursuing steelhead trout – the ocean-going form of rainbow trout – already know that you have to pay your dues. It’s well worth the effort when we achieve a solid hook set into the awesome power of the famed silver torpedoes. So, how should we pick the prime days to be on the water to increase the probability of success?

Sorry, I’m a bit of a statistics nut, but I like to improve my odds and predict success when at all possible. Some may say that there are “liars, damned liars and then, finally, statisticians.” While we can argue this for fun over a beer, the bottom line is that data does not lie.

contour plot showing relationship between fishing success and barometric pressure

I assimilate all kinds of data after every fishing trip, trying to perfect the ideal model to optimize my selection of the perfect fishing day (yes, I fish during the imperfect days as well). While there are many variables to consider, such as air and water temperature, cloud cover, flows, turbidity and, of course, the angler, don’t ignore the barometer.

Barometric pressure is a very reliable factor to watch. It’s best to consider not only the current readings, but whether pressure is steady, rising or falling. Also note what the trend has been up to that point: steady, rising or falling.

If we consider the contour plot above, which I created using JMP software, we can see the preferred barometer range for reliable steelhead fishing is between 29.9 and 30.35. The colored areas in the plot – defined in the Fish-On legend at right – show the number of fish caught during my fishing expeditions. The Barometer variable is straightforward. Current Trend describes the barometric trend at the time: 0 is falling, 1 is steady, and 2 is rising.

Extremely high and low barometric readings generally equate to a tough day in the snow and cold. Steady readings between 29.9 and 30.35 usually will yield a decent day and result in solid hook-ups. Because the winter can bring frequent frontal changes to our area, the fish can get finicky or sometimes present the dreaded “lock-jaw” effect (that is, no bites), which is when generally the barometric pressure is low and falling or moderate to high and rising. If barometric pressures are changing, I generally prefer rising pressure, especially following frontal lows.

For the statisticians in the audience, there certainly is a fair amount of noise present in this analysis because of the many other variables I mentioned earlier; but if you pay attention to these principles, your success rates will improve. For those of you who use your precious vacation days to go fishing, try these guidelines to plan for success!

Community Member

James T Metz wrote:

Leo, interesting analysis. One suggestion. I would display the data points on your contour plot. That will give the reader a better sense of how many data points "support" the construction of the various colored contours. I too have constructed these types of contour plots and have endured criticism from colleagues because the contours constructed were created by only a few sparse data points. Nonetheless. Interesting analysis! Jim Metz

Community Member

Listening to the Voice of the Customer - JMP Blog wrote:

[...] too. Look for our Six Sigma specialist Leo Wright, who recently posted about using JMP to improve success in fly fishing. tags: Data Visualization, JMP 7, Visual Six Sigma Bookmark on Delicious Digg this post Recommend [...]