regression - What is a strict definition of U-shaped relationship? - Cross Validated
Synonyms for curve at hair-restore.info with free online thesaurus, antonyms, and definitions. Find descriptive alternatives for curve. A humped yield curve is a relatively rare type of yield curve that results when the interest rates on Dictionary · Investing · The 4 Best S&P Index Funds · World's Top 20 Economies · Stock Basics DEFINITION of Humped Yield Curve Humped yield curves are also known as bell-shaped curves. Definition. The financial investing term humped yield curve refers to a bell- shaped curve, indicating mid-term rates that exceed both long and short term rates.
A U-shape is a function with exactly one turning point. This corresponds to a function that is quasi-convex but not monotone. One complication that comes up is what if the turning point is close to the ends of the range of the x variable? Should we still consider such a function a U-shape?
In my opinion, such a discussion should be had when you define what a U-shape means to you for your application, and when you specify your null hypothesis. Arbitrary decisions are necessary with this proposed framework. The important thing is to be open about them and check how sensitive results are to changes and to challenge others to do the same.
Learning curve - Wikipedia
In addition to stating the null hypothesis, as always you should state the assumptions you rely on. For example, a common assumption is that the regression function is either U-shaped on monotone.
The Appropriate Test for a U-Shaped Relationship", where they propose an improvement on the vanilla OLS quadratic test by testing that the derivative of a specified functional form is negative at the beginning of the range, and positive at the end. An additional point to consider is: Do you want a test that rejects the null hypothesis because of a small violation of U-shapedness?
If yes, consider the R package qmutestwhich implements a non-parametric tests based on splines of the null hypotheses that the regression function is quasi-convex, and separately that it is monotone. General learning limits[ edit ] Learning curves, also called experience curves, relate to the much broader subject of natural limits for resources and technologies in general. Such limits generally present themselves as increasing complications that slow the learning of how to do things more efficiently, like the well-known limits of perfecting any process or product or to perfecting measurements.
Approaching limits of perfecting things to eliminate waste meets geometrically increasing effort to make progress, and provides an environmental measure of all factors seen and unseen changing the learning experience. Perfecting things becomes ever more difficult despite increasing effort despite continuing positive, if ever diminishing, results.
hum-shape [hump-shape] | WordReference Forums
The same kind of slowing progress due to complications in learning also appears in the limits of useful technologies and of profitable markets applying to product life cycle management and software development cycles. Remaining market segments or remaining potential efficiencies or efficiencies are found in successively less convenient forms.
Efficiency and development curves typically follow a two-phase process of first bigger steps corresponding to finding things easier, followed by smaller steps of finding things more difficult. It reflects bursts of learning following breakthroughs that make learning easier followed by meeting constraints that make learning ever harder, perhaps toward a point of cessation.
Natural Limits One of the key studies in the area concerns diminishing returns on investments generally, either physical or financial, pointing to whole system limits for resource development or other efforts. The energy needed to produce energy is a measure of our difficulty in learning how to make remaining energy resources useful in relation to the effort expended. Energy returns on energy invested have been in continual decline for some time, caused by natural resource limits and increasing investment.
Energy is both nature's and our own principal resource for making things happen. The point of diminishing returns is when increasing investment makes the resource more expensive. As natural limits are approached, easily used sources are exhausted and ones with more complications need to be used instead.
As an environmental signal persistently diminishing EROI indicates an approach of whole system limits in our ability to make things happen. When complications emerge to limit learning progress the limit of useful returns, uR, is approached and R-uR approaches zero.
That point is approached as a vertical asymptote, at a particular point in time, that can be delayed only by unsustainable effort. It defines a point at which enough investment has been made and the task is done, usually planned to be the same as when the task is complete.
For unplanned tasks it may be either foreseen or discovered by surprise. The usefulness measure, uR, is affected by the complexity of environmental responses that can only be measured when they occur unless they are foreseen. In culture[ edit ] "Steep learning curve"[ edit ] The expression steep learning curve is used with opposite meanings. A steeper hill is initially hard, while a gentle slope is less strainful, though sometimes rather tedious.
Accordingly, the shape of the curve hill may not indicate the total amount of work required. Instead, it can be understood as a matter of preference related to ambition, personality and learning style. Short and long learning curves Fig Product A has lower functionality and a short learning curve. Product B has greater functionality but takes longer to learn The term learning curve with meanings of easy and difficult can be described with adjectives like short and long rather than steep and shallow.
- Learning curve
Fig 9 On the other hand, if two products have different functionality, then one with a short curve a short time to learn and limited functionality may not be as good as one with a long curve a long time to learn and greater functionality.
Fig 10 For example, the Windows program Notepad is extremely simple to learn, but offers little after this. At the other extreme is the UNIX terminal editor vi or Vimwhich is difficult to learn, but offers a wide array of features after the user has learned how to use it. Unfortunately, people didn't start talking that way until the s. He identifies the first use of steep learning curve asand the arduous interpretation as