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© 2009 Plant Management Network. A Comparison of Two Devices Used to Measure Golf Course Putting Green Speed Jacob S. Richards and Douglas E. Karcher, Department of Horticulture, University of Arkansas, Fayetteville, AR 72701; Thomas A. Nikolai, Department of Crop and Soil Sciences, Michigan State University, East Lansing, MI 48824; Jason J. Henderson, Department of Plant Science, University of Connecticut, Storrs, CT 06269; and John C. Sorochan, Department of Plant Sciences, University of Tennessee, Knoxville, TN 37996 Corresponding author: Douglas E. Karcher. karcher@uark.edu Richards, J. S., Karcher, D. E., Nikolai, T. A., Henderson, J. J., and Sorochan, J. C. 2009. A comparison of two devices used to measure golf course putting green speed. Online. Applied Turfgrass Science doi:10.1094/ATS-2009-0724-02-RS. Abstract The Stimpmeter and Pelzmeter are two devices commonly used to measure putting green speed. The Stimpmeter was released in 1978 and the Pelzmeter followed approximately 25 years later. The Pelzmeter uses various technologies to potentially reduce measurement variability. However, it is unclear how similar these meters compare for measuring putting green speed. The objective of this research was to compare the measurement variability between the two devices when measuring putting green speed and to determine if they give similar results on the same putting surface. This study was conducted at four sites: the University of Arkansas (Fayetteville, AR); the University of Tennessee (Knoxville, TN); the University of Connecticut (Storrs, CT); and Michigan State University (East Lansing, MI). At each site, three evaluators used each device to measure putting green speed on plots with varying green speeds. There was a strong linear, one-to-one relationship between the Pelzmeter and the Stimpmeter when measuring putting green speed on the same turf. Measurement repeatability (as measured by standard deviation) among different evaluators was improved with the Pelzmeter at one of the four sites. There were no differences in measurement repeatability between the devices when a single evaluator repeatedly measured the same turf with the same device. Background Information on Putting Green Speed Measurement Putting green speed is an important aspect of a putting green’s overall quality and according to a Golf Course Superintendents Association of America survey, the most common complaint from golfers to golf course superintendents about golf course conditions is that putting green speeds are too slow (4). Putting green speed is the estimated distance a ball travels after being released from an inclined plane or after being struck with a putter. In the 1970s, the United States Golf Association (USGA) recognized that green speed was an important aspect of the game of golf and commissioned the development of an instrument to estimate the speed of putting greens. Subsequently, the Stimpmeter was released in 1978 and remains the only tool accepted by the USGA for estimating putting green speed (14). The Stimpmeter provides golf course superintendents a way to measure putting green consistency throughout the golf course and has been the prominent tool used in turfgrass research where putting green speed is evaluated. Past studies used the Stimpmeter to measure putting green speed as affected by nitrogen fertilization and the growth regulator trinexapec-ethyl (10), bermudagrass (Cynodon spp.) genotypes (2), overseeding ‘Tifdwarf’ bermudagrass (Cynodon trasvaalensis) putting greens (5), different mowing equipment (8), and light-weight rolling (6). Until recently, the Stimpmeter was the only tool used for research to measure putting green speed. The Stimpmeter is a v-shaped aluminum ramp that is 91 cm long and has a precisely milled ball-release notch 76 cm from the end, which is placed on the ground (Fig. 1A). To operate the Stimpmeter, a golf ball is placed in the notch and then the operator slowly raises the notched end until the ball starts to roll down the ramp. Once the ball starts to roll, the Stimpmeter must be held steady until the ball reaches the putting surface to ensure measurement accuracy. The distance travelled by the ball from the end of the ramp is then measured (1). The Stimpmeter poses some potential shortcomings that may increase its potential for error (11). If the Stimpmeter is not slowly lifted or is lifted in a jerky motion, green speed measurements can be flawed. Also, when using the Stimpmeter, there is an opportunity for ball bounce to occur as the golf ball makes the transition from the ramp to the putting surface, which may influence the green speed measurements. Finally, tracking effects may occur when the Stimpmeter is used in the same fixed position for consecutive ball rolls. Under these circumstances, subsequent golf balls that are rolled meet less resistance by grass blades that have been laid down by the previous ball (11,13).
In 2003, the Pelzmeter was released as an alternative instrument for measuring putting green speed (Fig. 1B). The Pelzmeter was designed to reduce variability associated with the Stimpmeter by implementing a bubble-level system to ensure the ball is released from a consistent height, and a tapered ramp, which releases balls horizontally onto the green to minimize ball bounce. The Pelzmeter’s three side-by-side grooves help to minimize ball tracking effects (13). Because it is relatively new to the turf industry and is not endorsed by the USGA, the Pelzmeter has been used much less than the Stimpmeter for putting green speed research. However, recent studies have used the Pelzmeter to determine the effect that various mowing treatments and rolling treatments had on putting green speed (12), and the Pelzmeter was also used to determine the speed of nine putting greens that were mowed using various bedknife thicknesses (3). Undoubtedly, turfgrass research evaluating putting green speed will continue at various sites with some using the Stimpmeter and others the Pelzmeter to measure green speed. Therefore, it is important to know if results obtained from the two devices are comparable. Also, there is a need to substantiate claims that the Pelzmeter reduces measurement variability that is associated with the Stimpmeter. The objective of this study was to determine if the Stimpmeter and Pelzmeter give similar results on the same putting surface and if there are differences in measurement repeatability between two devices. Methodology for Comparing the Stimpmeter and Pelzmeter Experimental area. This study was conducted at four sites: the University of Arkansas (ARK), Fayetteville, AR; the University of Tennessee (TENN), Knoxville, TN; the University of Connecticut (CONN), Storrs, CT; and Michigan State University (MSU), East Lansing, MI. The experimental area at each site is summarized in Table 1. Putting green root zones and species varied across sites. At ARK and TENN, putting greens were built on a USGA specification rootzone (15) and at CONN and MSU putting greens were built on native soil. Table 1. Experimental areas at each research site.
x ARK = Arkansas Agricultural Research and Extension Center (Fayetteville, AR); CONN = University of Connecticut Plant Science Research and Education Facility (Storrs, CT); MSU = Hancock Turfgrass Research Center (East Lansing, MI); TENN = University of Tennessee East Tennessee Research and Education Center (Knoxville, TN). y Constructed according to USGA specifications (15). Meter evaluations. This study contained two main treatment factors: the device for measuring putting green speed (Pelzmeter and Stimpmeter) and the evaluator using the device (three evaluators at each site). At each site, ball roll distance was measured by each evaluator with each device on each of eight plots (except TENN where ten plots were used) maintained under varying cultural management practices. A range of green speeds was present on the plots at all sites as the result of a concurrent study comparing the effects of various combinations of mowing height (3 to 4 mm), mowing frequency (3 to 6 days/week), and rolling frequency (0 to 6 days/week) on putting green speed and turf quality (12). Putting green speed was determined by measuring ball roll distance for the Pelzmeter and for the Stimpmeter according to standard procedures, which included rolling three golf balls in opposite directions and the six resultant ball roll distances were averaged on each plot (7,13). Three evaluators were assigned to use each device three times in a random order on each plot. However, at MSU, each evaluator used each device only once per plot due to time constraints that resulted from a repeatedly malfunctioning prototype meter (the prototype meter was dropped from evaluation at the other three sites and is not discussed further in this report). Statistical analysis. Regression analysis was computed using PROC REG in SAS (SAS Institute Inc., Cary, NC) to compare the average putting green speeds of each plot as measured by the Pelzmeter to those measured by the Stimpmeter. For each device, standard deviations (with 95% confidence intervals) were calculated to determine measurement repeatability with each device. Standard deviations were calculated for the variation among different evaluators when measuring the same plot with the same device, and for the variation within a single evaluator when repeatedly measuring the same plot with the same device. Measurement Correlation and Precision Between the Stimpmeter and Pelzmeter Regression analysis revealed a strong linear relationship between the Stimpmeter and the Pelzmeter across a wide range of ball roll distances (265 to 360 cm) (Fig. 2). In addition, the regression line slope and intercept were close to (and not significantly different from) 1.0 and 0.0, respectively. The strong linear relationship was present across all four experimental sites, which included a variety of grass species and soil types (Table 1). This indicates that green speed measurements taken with the Pelzmeter can be expected to be very similar to those measured with the Stimpmeter. Therefore, ball roll distances from previous research with the Stimpmeter are comparable to studies that use the Pelzmeter.
While there was evidence that the Pelzmeter reduced measurement variability among evaluators at the CONN site (Fig. 3), there were no significant differences among the meters at the other three sites. Measurement variation was higher at MSU (Fig. 3), which was likely due to ball roll distances being calculated from a single sample at MSU, whereas three sub-samples were averaged per evaluator at the other three sites. At all four sites, measurement variability for each device was less than 15 cm. This distance is less than the difference in green speed at which an average golfer is likely to detect, according to a 2001 survey (9).
Meters did not differ in measurement repeatability when the same evaluator made multiple measurements on the same turf (Fig. 4). Considering these results, variation in green speed measurements when evaluated on the same turf should not be attributed to the device or the evaluator, as long as proper operating procedures for each device are followed. Measurement variation is most likely the result of other factors, such as varying wind speed and direction during measurement, non-uniform surface conditions, and differences in turf orientation, perhaps due to grain or mowing patterns.
Both of these instruments are suitable for measuring green speed if they are used properly, and each provides certain advantages and disadvantages for the user. The Stimpmeter is less expensive and easier to handle and transport, but may have a greater potential for operator error. Evaluators in this trial had previous experience using the Stimpmeter, so the chance of operator error was minimized. However, untrained operators would be more likely to cause errors by raising the Stimpmeter with a jerky motion or by not holding the ramp steady as the golf ball is rolling off. The Pelzmeter takes longer to set up; however, operator error is minimized and since all three balls can be released at the same time, usually without hitting one another, it is often quicker for a single individual to take tape measurements. Therefore, turfgrass researchers and golf course superintendents can choose the green speed measuring device that best fits their situation. The strong linear, one-to-one relationship that exists between the two devices should provide researchers and golf course superintendents with confidence that the Pelzmeter and the Stimpmeter are similarly effective in evaluating putting green speed. Literature Cited 1. Anonymous. 2009. Stimpmeter instruction booklet. Online. USGA, Far Hills, NJ. 2. Busey, P., and Boyer, S. E. 1997. Golf ball roll friction of Cynodon genotypes. Intl. Turfgr. Soc. Res. J. 8:59-63. 3. Carson, T. 2007. The bedknife vs the green. Golf Course Maint. 75:42. 5. Grossi, N., Volterrani, M., Gaetani, M., Lulli, F., Magni, S., Croce, P., De Luca, A., and Mocioni, M. 2008. Bermudagrass putting green overseeding with coolseason turfgrasses in coastal Tuscany. Eur. Turfgrass Soc. Conf. Proc. 1:87-88. 6. Hartwiger, C. E., Peacock, C. H., DiPaola, J. M., and Cassel, D. 2001. Impact of light-weight rolling on putting green performance. Crop Sci. 41:1179-1184. 7. Hoos, D. E. 1982. The Green Section’s Stimpmeter: most think friend to some think enemy. USGA Green Sect. Rec. 20:2-3. 8. Jang, Y. B., and Shim, K. K. 2004. Comparative study on the green speed by different the types of putting green maintenance equipment. Korean J. Turfgr. Sci. 18:37-46. 9. Karcher, D., Nikolai, T., and Calhoun, R. 2001. Golfer's perceptions of greens speeds vary: Over typical Stimpmeter distances, golfers are only guessing when ball-roll differences are less than 6 inches. Golf Course Manage. 69:57-60. 10. McCullough, P. E., Haibo, L., McCarty, L. B., and Toler, J. E. 2006. Bermudagrass putting green performance influenced by nitrogen and trinexapac-ethyl. HortSci. 41:802-804. 11. Pelz, D. 2002. An improved apparatus and technique for measuring green-speed. Science and Golf IV. E. Thain, ed. Routledge, London, UK. 12. Richards, J., Karcher, D. E., Nikolai, T. A., Richardson, M. D., Patton, A. J., and Landreth, J. W. 2008. Mowing height, mowing frequency, and rolling frequency affect putting green speed. Speed. Arkansas Turfgrass Report 2007, Ark. Ag. Exp. Stn. Res. Ser. 557:52-56. 13. Pelzmeter User Manual. 2004. Pelzmeter Accurate Green-Speed. Spicewood, TX. 14. Thomas, F. W. 1983. How it all began. USGA Green Sect. Rec. 21:10-11. 15. USGA Green Section Staff. 1993. USGA recommendations for a method of putting green construction. USGA Green Sect. Rec. 31:1-3. |
