Archive for the ‘error’ Category

Self-Sustaining Sustainability

August 6, 2018

After decades of efforts and massive resources expended in trying to create a self-sustaining sustainable economy, perhaps it is time to wonder if we are going about it the wrong way. There seems to be truly significant and widespread desire for change, but the often inspiring volumes of investments and ingenuity applied to the problem persistently prove insufficient to the task. Why?

I’ve previously and repeatedly explained how finding the will to change is not the issue. This time I’ll approach my proposed solution in a different way.

Q: How do we create a self-sustaining sustainable economy?

A: By making sustainability profitable in monetary terms as well as in the substantive real terms of the relationships we live out with each other and the earth. Current efforts in this regard focus solely on reducing energy costs enough to compensate for investments in advancing the organizational mission. We need far more comprehensively designed solutions than that.

Q: How do we do that?

A: By financially rewarding improved sustainability at every level of innovation, from the individual to the community to the firm.

Q: How do we do that?

A: By instituting rights to the ownership of human, social, and natural capital properties, and by matching the demand for sustainability with the supply of it in a way that will inform arbitrage and pricing.

Q: How do we do that?

A: By lowering the cost of the information needed to be able to know how many shares of human, social, and natural capital stocks are owned, and to match demand with supply.

Q: How could that be done?

A: By investing as a society in improving the quality and distribution of the available information.

Q: What does that take?

A: Creating dependable and meaningful tools for ascertaining the quantity, quality, and type of sustainability impacts on human, social, and natural capital being offered.

Q: Can that be done?

A: The technical art and science of measurement needed for creating these tools is well established, having been in development for almost 100 years.

Q: How do we start?

A: An important lesson of history is that building the infrastructure and its array of applications follows in the wake of, and cannot precede, the institution of the constitutional ideals. We must know what the infrastructure and applications will look like in their general features, but nothing will ever be done if we think we have to have them in place before instantiating the general frame of reference. The most general right to own legal title to human, social, and natural capital can be instituted, and the legal status of new metric system units can be established, before efforts are put into unit standards, traceability processes, protocols for intralaboratory ruggedness tests and interlaboratory round robin trials, conformity assessments, etc.

Q: It sounds like an iterative process.

A: Yes, one that must attend from the start to the fundamental issues of information coherence and complexity, as is laid out in my recent work with Emily Oon, Spencer Benson, Jack Stenner, and others.

Q: This sounds highly technical, utilitarian, and efficient. But all the talk of infrastructure, standards, science, and laboratories sounds excessively technological. Is there any place in this scheme for ecological values, ethics, and aesthetics? And how are risk and uncertainty dealt with?

A: We can take up each of these in turn.

Ecological values: To use an organic metaphor, we know the DNA of the various human, social, and natural capital forms of life, or species, and we know their reproductive and life cycles, and their ecosystem requirements. What we have not done is to partner with each of these species in relationships that focus on maximizing the quality of their habitats, their maturation, and the growth of their populations. Social, psychological, and environmental relationships are best conceived as ecosystems of mutual interdependencies. Being able to separate and balance within-individual, between-individual, and collective levels of complexity in these interdependencies will be essential to the kinds of steward leadership needed for creating and maintaining new sociocognitive ecosystems. Our goal here is to become the change we want to institute, since caterpillar to butterfly metamorphoses come about only via transformations from within.

Ethics: The motivating intention is to care simultaneously and equally effectively for both individual uniqueness and global humanity. In accord with the most fundamental ethical decision, we choose discourse over violence, and we do so by taking language as the model for how things come into words. Language is itself alive in the sense of the collective processes by which new meanings come into it. Language moreover has the remarkable capacity of supporting local concrete improvisations and creativity at the same time that it provides navigable continuity and formal ideals. Care for the unity and sameness of meaning demands a combination of rigorous conceptual determinations embodied in well-defined words with practical applications of those words in local improvisations. That is how we support the need to make decisions with inevitably incomplete and inconsistent information while not committing the violence of the premature conclusion. The challenge is one of finding a balance between openness and boundaries that allows language and our organizational cultures to be stable while also evolving. Our technical grasp of complex adaptive systems, autopoiesis, and stochastic measurement information models is advanced enough to meet these ethical requirements of caring for ourselves, each other, and the earth.

Aesthetics: An aesthetic desire for and love of beauty roots the various forms of life inhabiting diverse niches in the proposed knowledge ecosystem and information infrastructure, and does so in the ground of the ethical choice of discourse and meaning over violence. The experience of beauty teaches us how to understand meaning. The attraction to beauty is a unique human phenomenon because it combines apparent opposites into a single complex feeling. Even when the object of desire is possessed as fully as possible, desire is not eliminated, and even when one feels the object of desire to be lost or completely out of touch, its presence and reality is still felt. So, too, with meaning: no actual instance of anything in the world ever embodies the fullness of an abstract conceptual ideal. This lesson of beauty is perhaps most plainly conveyed in music, where artists deliberately violate the standards of instrument tuning to create fascinating and absorbing combinations of harmony and dissonance from endlessly diverse ensembles. Some tunings persist beyond specific compositions to become immediately identifiable trademark sounds. In taking language as a model, the aesthetic combination of desire and possession informs the ethics of care for the unity and sameness of meaning, and vice versa. And ecological values, ethics, and aesthetics stand on par with the technical concerns of calibration and measurement.

Risk and uncertainty: Calibrating a tool relative to a unit standard is by itself already a big step toward reducing uncertainty and risk. Instead of the chaos of dozens of disconnected sustainability indicators, or the cacophony of hundreds or thousands of different tests, assessments, or surveys measuring the same things, we will have data and theory supporting interpretation of reproducible patterns. These patterns will be, and in many cases already are, embodied in instruments that further reduce risk by defining an invariant unit of comparison, simplifying interpretation, reducing opportunities for mistakes, by quantifying uncertainty, and by qualifying it in terms of the anomalous exceptions that depart from expectations. Each of these is a special feature of rigorously defined measurement that will eventually become the expected norm for information on sustainability.

For more on these themes, see my other blog posts here, my various publications, and my SSRN page.

 

Creative Commons License
LivingCapitalMetrics Blog by William P. Fisher, Jr., Ph.D. is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.
Based on a work at livingcapitalmetrics.wordpress.com.
Permissions beyond the scope of this license may be available at http://www.livingcapitalmetrics.com.

Advertisements

How bad will the financial crises have to get before…?

April 30, 2010

More and more states and nations around the world face the possibility of defaulting on their financial obligations. The financial crises are of epic historical proportions. This is a disaster of the first order. And yet, it is so odd–we have the solutions and preventative measures we need at our finger tips, but no one knows about them or is looking for them.

So,  I am persuaded to once again wonder if there might now be some real interest in the possibilities of capitalizing on

  • measurement’s well-known capacity for reducing transaction costs by improving information quality and reducing information volume;
  • instruments calibrated to measure in constant units (not ordinal ones) within known error ranges (not as though the measures are perfectly precise) with known data quality;
  • measures made meaningful by their association with invariant scales defined in terms of the questions asked;
  • adaptive instrument administration methods that make all measures equally precise by targeting the questions asked;
  • judge calibration methods that remove the person rating performances as a factor influencing the measures;
  • the metaphor of transparency by calibrating instruments that we really look right through at the thing measured (risk, governance, abilities, health, performance, etc.);
  • efficient markets for human, social, and natural capital by means of the common currencies of uniform metrics, calibrated instrumentation, and metrological networks;
  • the means available for tuning the instruments of the human, social, and environmental sciences to well-tempered scales that enable us to more easily harmonize, orchestrate, arrange, and choreograph relationships;
  • our understandings that universal human rights require universal uniform measures, that fair dealing requires fair measures, and that our measures define who we are and what we value; and, last but very far from least,
  • the power of love–the back and forth of probing questions and honest answers in caring social intercourse plants seminal ideas in fertile minds that can be nurtured to maturity and Socratically midwifed as living meaning born into supportive ecologies of caring relations.

How bad do things have to get before we systematically and collectively implement the long-established and proven methods we have at our disposal? It is the most surreal kind of schizophrenia or passive-aggressive avoidance pathology to keep on tormenting ourselves with problems for which we have solutions.

For more information on these issues, see prior blogs posted here, the extensive documentation provided, and http://www.livingcapitalmetrics.com.

Creative Commons License
LivingCapitalMetrics Blog by William P. Fisher, Jr., Ph.D. is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.
Based on a work at livingcapitalmetrics.wordpress.com.
Permissions beyond the scope of this license may be available at http://www.livingcapitalmetrics.com.

Reliability Coefficients: Starting from the Beginning

August 31, 2009

[This posting was prompted by questions concerning a previous blog entry, Reliability Revisited, and provides background on reliability that only Rasch measurement practitioners are likely to possess.] Most measurement applications based in ordinal data do not implement rigorous checks of the internal consistency of the observations, nor do they typically use the log-odds transformation to convert the nonlinear scores into linear measures. Measurement is usually defined in statistical terms, applying population-level models to obtain group-level summary scores, means, and percentages. Measurement, however, ought to involve individual-level models and case-specific location estimates. (See one of my earlier blogs for more on this distinction between statistics and measurement.)

Given the appropriate measurement focus on the individual, the instrument is initially calibrated and measures are estimated in a simultaneous conjoint process. Once the instrument is calibrated, the item estimates can be anchored, measures can be routinely produced from them, and new items can be calibrated into the system, and others dropped, over time. This method has been the norm in admissions, certification, licensure, and high stakes testing for decades (Fisher & Wright, 1994; Bezruczko, 2005).

Measurement modelling of individual response processes has to be stochastic, or else we run into the attenuation paradox (Engelhard, 1993, 1994). This is the situation in which a deterministic progression of observations from one end of the instrument to the other produces apparently error-free data strings that look like this (1 being a correct answer, a higher rating, or the presence of an attribute, and 0 being incorrect, a lower rating, or the absence of the attribute):

00000000000

10000000000

11000000000

11100000000

11110000000

11111000000

11111100000

11111111000

11111111100

11111111110

11111111111

In this situation, strings with all 0s and all 1s give no information useful for estimating measures (rows) or calibrations (columns). It is as though some of the people are shorter than the first unit on the ruler, and others are taller than the top unit. We don’t really have any way of knowing how short or tall they are, so their rows drop out. But eliminating the top and bottom rows makes the leftmost and rightmost columns all 0s and 1s, and eliminating them then gives new rows with all 0s and 1s, etc., until there’s no data left. (See my Revisiting Reliability blog for evaluations of five different probabilistically-structured data sets of this kind simulated to contrast various approaches to assessing reliability and internal consistency.)

The problem for estimation (Linacre, 1991, 1999, 2000) in data like those shown above is that the lack of informational overlaps between the columns, on the one hand, and between the rows, on the other, gives us no basis for knowing how much more of the variable is represented by any one item relative to any other, or by any one person measured relative to any other. In addition, whenever we actually construct measures of abilities, attitudes, or behaviors that conform with this kind of Guttman (1950) structure (Andrich, 1985; Douglas & Wright, 1989; Engelhard, 2008), the items have to be of such markedly different difficulties or agreeabilities that the results tend to involve large numbers of indistinguishable groups of respondents. But when that information is present in a probabilistically consistent way, we have an example of the phenomenon of stochastic resonance (Fisher, 1992b), so called because of the way noise amplifies weak deterministic signals (Andò & Graziani, 2000; Benzi, Sutera, & Vulpiani, 1981; Bulsara & Gammaitoni, 1996; Dykman & McClintock, 1998; Schimansky-Geier, Freund, Neiman, & Shulgin, 1998).

We need the noise, but we can’t let it overwhelm the system. We have to be able to know how much error there is relative to actual signal. Reliability is traditionally defined (Guilford 1965, pp. 439-40) as an estimate of this relation of signal and noise:

“The reliability of any set of measurements is logically defined as the proportion of their variance that is true variance…. We think of the total variance of a set of measures as being made up of two sources of variance: true variance and error variance… The true measure is assumed to be the genuine value of whatever is being measured… The error components occur independently and at random.”

Traditional reliability coefficients, like Cronbach’s alpha, are correlational, implementing a statistical model of group-level information. Error is taken to be the unexplained portion of the variance:

“In his description of alpha Cronbach (1951) proved (1) that alpha is the mean of all possible split-half coefficients, (2) that alpha is the value expected when two random samples of items from a pool like those in the given test are correlated, and (3) that alpha is a lower bound to the proportion of test variance attributable to common factors among the items” (Hattie, 1985, pp. 143-4).

But measurement models of individual-level response processes (Rasch, 1960; Andrich, 1988; Wright, 1977; Fisher & Wright, 1994; Bond & Fox, 2007; Wilson, 2005; Bezruczko, 2005) employ individual-level error estimates (Wright, 1977; Wright & Stone, 1979; Wright & Masters, 1982), not correlational group-level variance estimates. The individual measurement errors are statistically equivalent to sampling confidence intervals, as is evident in both Wright’s equations and in plots of errors and confidence intervals (see Figure 4 in Fisher, 2008). That is, error and confidence intervals both decline at the same rate with larger numbers of item responses per person, or larger numbers of person responses per item.

This phenomenon has a constructive application in instrument design. If a reasonable expectation for the measurement standard deviation can be formulated and related to the error expected on the basis of the number of items and response categories, a good estimate of the measurement reliability can be read off a nomograph (Linacre, 1993).

Wright (Wright & Masters, 1982, pp. 92, 106; Wright, 1996) introduced several vitally important measurement precision concepts and tools that follow from access to individual person and item error estimates. They improve on the traditional KR-20 or Cronbach reliability coefficients because the individualized error estimates better account for the imprecisions of mistargeted instruments, and for missing data, and so more accurately and conservatively estimate reliability.

Wright and Masters introduce a new reliability statistic, G, the measurement separation reliability index. The availability of individual error estimates makes it possible to estimate the true variance of the measures more directly, by subtracting the mean square error from the total variance. The standard deviation based on this estimate of true variance is then made the numerator of a ratio, G, having the root mean square error as its denominator.

Each unit increase in this G index then represents another multiple of the error unit in the amount of quantitative variation present in the measures. This multiple is nonlinearly represented in the traditional reliability coefficients expressed in the 0.00 – 1.00 range, such that the same separation index unit difference is found in the 0.00 to 0.50, 0.50 to 0.80, 0.80 to 0.90, 0.90 to 0.94, 0.94 to 0.96, and 0.96 to 0.97 reliability ranges (see Fisher, 1992a, for a table of values; available online: see references).

G can also be estimated as the square root of the reliability divided by one minus the reliability. Conversely, a reliability coefficient roughly equivalent to Cronbach’s alpha is estimated as G squared divided by G squared plus the error variance. Because individual error estimates are inflated in the presence of missing data and when an instrument is mistargeted and measures tend toward the extremes, the Rasch-based reliability coefficients tend to be more conservative than Cronbach’s alpha, as these sources of error are hidden within the variances and correlations. For a comparison of the G separation index, the G reliability coefficient, and Cronbach’s alpha over five simulated data sets, see the Reliability Revisited blog entry.

Error estimates can be made more conservative yet by multiplying each individual error term by the larger of either 1.0 or the square root of the associated individual mean square fit statistic for that case (Wright, 1995). (The mean square fit statistics are chi-squares divided by their degrees of freedom, and so have an expected value of 1.00; see Smith (1996) for more on fit, and see my recent blog, Revisiting Reliability, for more on the conceptualization and evaluation of reliability relative to fit.)

Wright and Masters (1982, pp. 92, 105-6) also introduce the concept of strata, ranges on the measurement continuum with centers separated by three errors. Strata are in effect a more forgiving expression of the separation reliability index, G, since the latter approximates strata with centers separated by four errors. An estimate of strata defined as having centers separated by four errors is very nearly identical with the separation index. If three errors define a 95% confidence interval, four are equivalent to 99% confidence.

There is a particular relevance in all of this for practical applications involving the combination or aggregation of physical, chemical, and other previously calibrated measures. This is illustrated in, for instance, the use of chemical indicators in assessing disease severity, environmental pollution, etc. Though any individual measure of the amount of a chemical or compound is valid within the limits of its intended purpose, to arrive at measures delineating disease severity, overall pollution levels, etc., the relevant instruments must be designed, tested, calibrated, and maintained, just as any instruments are (Alvarez, 2005; Cipriani, Fox, Khuder, et al., 2005; Fisher, Bernstein, et al., 2002; Fisher, Priest, Gilder, et al., 2008; Hughes, Perkins, Wright, et al., 2003; Perkins, Wright, & Dorsey, 2005; Wright, 2000).

The same methodology that is applied in this work, involving the rating or assessment of the quality of the outcomes or impacts counted, expressed as percentages, or given in an indicator’s native metric (parts per million, acres, number served, etc.), is needed in the management of all forms of human, social, and natural capital. (Watch this space for a forthcoming blog applying this methodology to the scaling of the UN Millennium Development Goals data.) The practical advantages of working from calibrated instrumentation in these contexts include data quality evaluations, the replacement of nonlinear percentages with linear measures, data volume reduction with no loss of information, and the integration of meaningful and substantive qualities with additive quantities on annotated metrics.

References

Alvarez, P. (2005). Several noncategorical measures define air pollution. In N. Bezruczko (Ed.), Rasch measurement in health sciences (pp. 277-93). Maple Grove, MN: JAM Press.

Andò, B., & Graziani, S. (2000). Stochastic resonance theory and applications. New York: Kluwer Academic Publishers.

Andrich, D. (1985). An elaboration of Guttman scaling with Rasch models for measurement. In N. B. Tuma (Ed.), Sociological methodology 1985 (pp. 33-80). San Francisco, California: Jossey-Bass.

Andrich, D. (1988). Rasch models for measurement. (Vols. series no. 07-068). Sage University Paper Series on Quantitative Applications in the Social Sciences). Beverly Hills, California: Sage Publications.

Benzi, R., Sutera, A., & Vulpiani, A. (1981). The mechanism of stochastic resonance. Journal of Physics. A. Mathematical and General, 14, L453-L457.

Bezruczko, N. (Ed.). (2005). Rasch measurement in health sciences. Maple Grove, MN: JAM Press.

Bond, T., & Fox, C. (2007). Applying the Rasch model: Fundamental measurement in the human sciences, 2d edition. Mahwah, New Jersey: Lawrence Erlbaum Associates.

Bulsara, A. R., & Gammaitoni, L. (1996, March). Tuning in to noise. Physics Today, 49, 39-45.

Cipriani, D., Fox, C., Khuder, S., & Boudreau, N. (2005). Comparing Rasch analyses probability estimates to sensitivity, specificity and likelihood ratios when examining the utility of medical diagnostic tests. Journal of Applied Measurement, 6(2), 180-201.

Cronbach, L. J. (1951). Coefficient alpha and the internal structure of tests. Psychometrika, 16(3), 297-334.

Douglas, G. A., & Wright, B. D. (1989). Response patterns and their probabilities. Rasch Measurement Transactions, 3(4), 75-77 [http://www.rasch.org/rmt/rmt34.htm].

Dykman, M. I., & Mcclintock, P. V. E. (1998, January 22). What can stochastic resonance do? Nature, 391(6665), 344.

Engelhard, G., Jr. (1993). What is the attenuation paradox? Rasch Measurement Transactions, 6(4), 257 [http://www.rasch.org/rmt/rmt64.htm].

Engelhard, G., Jr. (1994). Resolving the attenuation paradox. Rasch Measurement Transactions, 8(3), 379.

Engelhard, G. (2008, July). Historical perspectives on invariant measurement: Guttman, Rasch, and Mokken. Measurement: Interdisciplinary Research & Perspectives, 6(3), 155-189.

Fisher, W. P., Jr. (1992a). Reliability statistics. Rasch Measurement Transactions, 6(3), 238 [http://www.rasch.org/rmt/rmt63i.htm].

Fisher, W. P., Jr. (1992b, Spring). Stochastic resonance and Rasch measurement. Rasch Measurement Transactions, 5(4), 186-187 [http://www.rasch.org/rmt/rmt54k.htm].

Fisher, W. P., Jr. (2008, Summer). The cash value of reliability. Rasch Measurement Transactions, 22(1), 1160-3 [http://www.rasch.org/rmt/rmt221.pdf].

Fisher, W. P., Jr., Bernstein, L. H., Qamar, A., Babb, J., Rypka, E. W., & Yasick, D. (2002, February). At the bedside: Measuring patient outcomes. Advance for Administrators of the Laboratory, 11(2), 8, 10 [http://laboratory-manager.advanceweb.com/Article/At-the-Bedside-7.aspx].

Fisher, W. P., Jr., Priest, E., Gilder, R., Blankenship, D., & Burton, E. C. (2008, July 3-6). Development of a novel heart failure measure to identify hospitalized patients at risk for intensive care unit admission. Presented at the World Congress on Controversies in Cardiovascular Diseases [http://www.comtecmed.com/ccare/2008/authors_abstract.aspx#Author15], Intercontinental Hotel, Berlin, Germany.

Fisher, W. P., Jr., & Wright, B. D. (Eds.). (1994). Applications of probabilistic conjoint measurement. International Journal of Educational Research, 21(6), 557-664.

Guilford, J. P. (1965). Fundamental statistics in psychology and education. 4th Edn. New York: McGraw-Hill.

Guttman, L. (1950). The basis for scalogram analysis. In S. A. Stouffer & et al. (Eds.), Studies in social psychology in World War II. volume 4: Measurement and prediction (pp. 60-90). New York: Wiley.

Hattie, J. (1985, June). Methodology review: Assessing unidimensionality of tests and items. Applied Psychological Measurement, 9(2), 139-64.

Hughes, L., Perkins, K., Wright, B. D., & Westrick, H. (2003). Using a Rasch scale to characterize the clinical features of patients with a clinical diagnosis of uncertain, probable or possible Alzheimer disease at intake. Journal of Alzheimer’s Disease, 5(5), 367-373.

Linacre, J. M. (1991, Spring). Stochastic Guttman order. Rasch Measurement Transactions, 5(4), 189 [http://www.rasch.org/rmt/rmt54p.htm].

Linacre, J. M. (1993). Rasch-based generalizability theory. Rasch Measurement Transactions, 7(1), 283-284; [http://www.rasch.org/rmt/rmt71h.htm].

Linacre, J. M. (1999). Understanding Rasch measurement: Estimation methods for Rasch measures. Journal of Outcome Measurement, 3(4), 382-405.

Linacre, J. M. (2000, Autumn). Guttman coefficients and Rasch data. Rasch Measurement Transactions, 14(2), 746-7 [http://www.rasch.org/rmt/rmt142e.htm].

Perkins, K., Wright, B. D., & Dorsey, J. K. (2005). Using Rasch measurement with medical data. In N. Bezruczko (Ed.), Rasch measurement in health sciences (pp. 221-34). Maple Grove, MN: JAM Press.

Rasch, G. (1960). Probabilistic models for some intelligence and attainment tests (Reprint, with Foreword and Afterword by B. D. Wright, Chicago: University of Chicago Press, 1980). Copenhagen, Denmark: Danmarks Paedogogiske Institut.

Schimansky-Geier, L., Freund, J. A., Neiman, A. B., & Shulgin, B. (1998). Noise induced order: Stochastic resonance. International Journal of Bifurcation and Chaos, 8(5), 869-79.

Smith, R. M. (2000). Fit analysis in latent trait measurement models. Journal of Applied Measurement, 1(2), 199-218.

Wilson, M. (2005). Constructing measures: An item response modeling approach. Mahwah, New Jersey: Lawrence Erlbaum Associates.

Wright, B. D. (1977). Solving measurement problems with the Rasch model. Journal of Educational Measurement, 14(2), 97-116 [http://www.rasch.org/memo42.htm].

Wright, B. D. (1995, Summer). Which standard error? Rasch Measurement Transactions, 9(2), 436-437 [http://www.rasch.org/rmt/rmt92n.htm].

Wright, B. D. (1996, Winter). Reliability and separation. Rasch Measurement Transactions, 9(4), 472 [http://www.rasch.org/rmt/rmt94n.htm].

Wright, B. D. (2000). Rasch regression: My recipe. Rasch Measurement Transactions, 14(3), 758-9 [http://www.rasch.org/rmt/rmt143u.htm].

Wright, B. D., & Masters, G. N. (1982). Rating scale analysis: Rasch measurement. Chicago, Illinois: MESA Press.

Wright, B. D., & Stone, M. H. (1979). Best test design: Rasch measurement. Chicago, Illinois: MESA Press.

Creative Commons License
LivingCapitalMetrics Blog by William P. Fisher, Jr., Ph.D. is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.
Based on a work at livingcapitalmetrics.wordpress.com.
Permissions beyond the scope of this license may be available at http://www.livingcapitalmetrics.com.