Showing papers by "University of Nebraska–Lincoln published in 2001"

The Relative Performance of Full Information Maximum Likelihood Estimation for Missing Data in Structural Equation Models

Abstract: A Monte Carlo simulation examined the performance of 4 missing data methods in structural equation models: full information maximum likelihood (FIML), listwise deletion, pairwise deletion, and similar response pattern imputation. The effects of 3 independent variables were examined (factor loading magnitude, sample size, and missing data rate) on 4 outcome measures: convergence failures, parameter estimate bias, parameter estimate efficiency, and model goodness of fit. Results indicated that FIML estimation was superior across all conditions of the design. Under ignorable missing data conditions (missing completely at random and missing at random), FIML estimates were unbiased and more efficient than the other methods. In addition, FIML yielded the lowest proportion of convergence failures and provided near-optimal Type 1 error rates across both simulations.

FLUXNET: A New Tool to Study the Temporal and Spatial Variability of Ecosystem-Scale Carbon Dioxide, Water Vapor, and Energy Flux Densities

Abstract: FLUXNET is a global network of micrometeorological flux measurement sites that measure the exchanges of carbon dioxide, water vapor, and energy between the biosphere and atmosphere. At present over 140 sites are operating on a long-term and continuous basis. Vegetation under study includes temperate conifer and broadleaved (deciduous and evergreen) forests, tropical and boreal forests, crops, grasslands, chaparral, wetlands, and tundra. Sites exist on five continents and their latitudinal distribution ranges from 70°N to 30°S. FLUXNET has several primary functions. First, it provides infrastructure for compiling, archiving, and distributing carbon, water, and energy flux measurement, and meteorological, plant, and soil data to the science community. (Data and site information are available online at the FLUXNET Web site, http://www-eosdis.ornl.gov/FLUXNET/.) Second, the project supports calibration and flux intercomparison activities. This activity ensures that data from the regional networks are intercomparable. And third, FLUXNET supports the synthesis, discussion, and communication of ideas and data by supporting project scientists, workshops, and visiting scientists. The overarching goal is to provide information for validating computations of net primary productivity, evaporation, and energy absorption that are being generated by sensors mounted on the NASA Terra satellite. Data being compiled by FLUXNET are being used to quantify and compare magnitudes and dynamics of annual ecosystem carbon and water balances, to quantify the response of stand-scale carbon dioxide and water vapor flux densities to controlling biotic and abiotic factors, and to validate a hierarchy of soil–plant–atmosphere trace gas exchange models. Findings so far include 1) net CO 2 exchange of temperate broadleaved forests increases by about 5.7 g C m −2 day −1 for each additional day that the growing season is extended; 2) the sensitivity of net ecosystem CO 2 exchange to sunlight doubles if the sky is cloudy rather than clear; 3) the spectrum of CO 2 flux density exhibits peaks at timescales of days, weeks, and years, and a spectral gap exists at the month timescale; 4) the optimal temperature of net CO 2 exchange varies with mean summer temperature; and 5) stand age affects carbon dioxide and water vapor flux densities.

Diversity and productivity in a long-term grassland experiment

Abstract: Plant diversity and niche complementarity had progressively stronger effects on ecosystem functioning during a 7-year experiment, with 16-species plots attaining 2.7 times greater biomass than monocultures. Diversity effects were neither transients nor explained solely by a few productive or unviable species. Rather, many higher-diversity plots outperformed the best monoculture. These results help resolve debate over biodiversity and ecosystem functioning, show effects at higher than expected diversity levels, and demonstrate, for these ecosystems, that even the best-chosen monocultures cannot achieve greater productivity or carbon stores than higher-diversity sites.

Critical factors for successful implementation of enterprise systems

Abstract: Enterprise resource planning (ERP) systems have emerged as the core of successful information management and the enterprise backbone of organizations. The difficulties of ERP implementations have been widely cited in the literature but research on the critical factors for initial and ongoing ERP implementation success is rare and fragmented. Through a comprehensive review of the literature, 11 factors were found to be critical to ERP implementation success – ERP teamwork and composition; change management program and culture; top management support; business plan and vision; business process reengineering with minimum customization; project management; monitoring and evaluation of performance; effective communication; software development, testing and troubleshooting; project champion; appropriate business and IT legacy systems. The classification of these factors into the respective phases (chartering, project, shakedown, onward and upward) in Markus and Tanis’ ERP life cycle model is presented and the importance of each factor is discussed.

The Physiology of Life History Trade-Offs in Animals

Abstract: ▪ Abstract The functional causes of life history trade-offs have been a topic of interest to evolutionary biologists for over six decades. Our review of life history trade-offs discusses conceptual issues associated with physiological aspects of trade-offs, and it describes recent advances on this topic. We focus on studies of four model systems: wing polymorphic insects, Drosophila, lizards, and birds. The most significant recent advances have been: (a) incorporation of genetics in physiological studies of trade-offs, (b) integration of investigations of nutrient input with nutrient allocation, (c) development of more sophisticated models of resource acquisition and allocation, (d) a shift to more integrated, multidisciplinary studies of intraspecific trade-offs, and (e) the first detailed investigations of the endocrine regulation of life history trade-offs.

Formation of ordered ice nanotubes inside carbon nanotubes.

Abstract: Following their discovery1, carbon nanotubes have attracted interest not only for their unusual electrical and mechanical properties, but also because their hollow interior can serve as a nanometre-sized capillary2,3,4,5,6,7, mould8,9,10,11 or template12,13,14 in material fabrication. The ability to encapsulate a material in a nanotube also offers new possibilities for investigating dimensionally confined phase transitions15. Particularly intriguing is the conjecture16 that matter within the narrow confines of a carbon nanotube might exhibit a solid–liquid critical point17 beyond which the distinction between solid and liquid phases disappears. This unusual feature, which cannot occur in bulk material, would allow for the direct and continuous transformation of liquid matter into a solid. Here we report simulations of the behaviour of water encapsulated in carbon nanotubes that suggest the existence of a variety of new ice phases not seen in bulk ice, and of a solid–liquid critical point. Using carbon nanotubes with diameters ranging from 1.1 nm to 1.4 nm and applied axial pressures of 50 MPa to 500 MPa, we find that water can exhibit a first-order freezing transition to hexagonal and heptagonal ice nanotubes, and a continuous phase transformation into solid-like square or pentagonal ice nanotubes.

Quorum Sensing in the Dimorphic Fungus Candida albicans Is Mediated by Farnesol

Abstract: The inoculum size effect in the dimorphic fungus Candida albicans results from production of an extracellular quorum-sensing molecule (QSM). This molecule prevents mycelial development in both a growth morphology assay and a differentiation assay using three chemically distinct triggers for germ tube formation (GTF): L-proline, N-acetylglucosamine, and serum (either pig or fetal bovine). In all cases, the presence of QSM prevents the yeast-to-mycelium conversion, resulting in actively budding yeasts without influencing cellular growth rates. QSM exhibits general cross-reactivity within C. albicans in that supernatants from strain A72 are active on five other strains of C. albicans and vice versa. The QSM excreted by C. albicans is farnesol (C(15)H(26)O; molecular weight, 222.37). QSM is extracellular, and is produced continuously during growth and over a temperature range from 23 to 43 degrees C, in amounts roughly proportional to the CFU/milliliter. Production is not dependent on the type of carbon source nor nitrogen source or on the chemical nature of the growth medium. Both commercial mixed isomer and (E,E)-farnesol exhibited QSM activity (the ability to prevent GTF) at a level sufficient to account for all the QSM activity present in C. albicans supernatants, i.e., 50% GTF at ca. 30 to 35 microM. Nerolidol was ca. two times less active than farnesol. Neither geraniol (C(10)), geranylgeraniol (C(20)), nor farnesyl pyrophosphate had any QSM activity.

Optical properties and nondestructive estimation of anthocyanin content in plant leaves.

Abstract: Absorption and reflectance spectra of maple (Acer platanoides), cotoneaster (Cotoneaster alaunica), dogwood (Cornus alba) and pelargonium (Pelargonium zonale) leaves with a wide range of pigment content and composition were studied in visible and near-infrared spectra in order to reveal specific anthocyanin (Anth) spectral features in leaves. Comparing absorption spectra of Anth-containing and Anth-free leaves with the same chlorophyll (Chl) content, absorption spectra of Anth in leaves were derived. The main spectral feature of Anth absorption in vivo was a peak around 550 nm; the peak magnitude was closely related to Anth content. A quantitative nondestructive technique was developed to subtract Chl contribution to reflectance in this spectral region and retrieve Anth content from reflectance over a wide range of pigment content and composition. Anth reflectance index in the form ARI = (R550)-1 - (R700)-1, where (R550)-1 and (R700)-1 are inverse reflectances at 550 and 700 nm, respectively, allowed an accurate estimation of Anth accumulation, even in minute amounts, in intact senescing and stressed leaves.

Mycobacterium avium subsp. paratuberculosis in Veterinary Medicine.

Abstract: Mycobacterium avium subsp. paratuberculosis (basonym M. paratuberculosis) is the etiologic agent of a severe gastroenteritis in ruminants known as Johne's disease. Economic losses to the cattle industry in the United States are staggering, reaching $1.5 billion annually. A potential pathogenic role in humans in the etiology of Crohn's disease is under investigation. In this article, we review the epidemiology, pathogenesis, diagnostics, and disease control measures of this important veterinary pathogen. We emphasize molecular genetic aspects including the description of markers used for strain identification, diagnostics, and phylogenetic analysis. Recent important advances in the development of animal models and genetic systems to study M. paratuberculosis virulence determinants are also discussed. We conclude with proposals for the applications of these models and recombinant technology to the development of diagnostic, control, and therapeutic measures.

Situational Interest: A Review of the Literature and Directions for Future Research

Abstract: This paper reviews theoretical and empirical research on situational interest. A distinction is made between situational and personal interest. The former is spontaneous and context-specific, whereas the latter is enduring and context-general. We summarize historical perspectives and recent empirical findings on situational interest. Five emergent themes are identified that focus on relationships among situational interest, information processing, and affective engagement. We also discuss important topics for future research.

Plant diversity enhances ecosystem responses to elevated CO2 and nitrogen deposition

Abstract: Human actions are causing declines in plant biodiversity, increases in atmospheric CO2 concentrations and increases in nitrogen deposition; however, the interactive effects of these factors on ecosystem processes are unknown. Reduced biodiversity has raised numerous concerns, including the possibility that ecosystem functioning may be affected negatively, which might be particularly important in the face of other global changes. Here we present results of a grassland field experiment in Minnesota, USA, that tests the hypothesis that plant diversity and composition influence the enhancement of biomass and carbon acquisition in ecosystems subjected to elevated atmospheric CO2 concentrations and nitrogen deposition. The study experimentally controlled plant diversity (1, 4, 9 or 16 species), soil nitrogen (unamended versus deposition of 4 g of nitrogen per m2 per yr) and atmospheric CO2 concentrations using free-air CO2 enrichment (ambient, 368 micromol mol-1, versus elevated, 560 micromol mol-1). We found that the enhanced biomass accumulation in response to elevated levels of CO2 or nitrogen, or their combination, is less in species-poor than in species-rich assemblages.

Soybean response to water : A QTL analysis of drought tolerance

Abstract: Soybean [Glycine max (L.) Merr.] yield, when regressed on water needed to replenish 0 to 100% seasonal evapotranspiration (ET), generates an estimate of season-specific water-use efficiency (WUE). The impact of unpredictable water deficits might be lessened if high-yielding genotypes had a smaller beta. Our objective was to determine the genetic basis of beta and carbon isotope discrimination (CID), a theorized indicator of transpiration efficiency (TE). A Minsoy' Noir I' population of 236 recombinant inbred lines (RILs), genotyped at 665 loci, was evaluated in six water treatements (100, 80, 60, 40, 20, and 0% ET) for 2 yr. Water stress was mild in 1994, but high temperatures and no rainfall in 1995 led to a drought so severe that the 100% ET treatment required 41 cm of irrigation. The 1995 yield-to-water regression was highly linear (28 kg ha -1 cm -1 ), Genotype × water (G × W) interaction was due to genotypic heterogeneity in beta. The CH) vs. beta correlation was low (r = 0.26), so selection for better leaf TE may not improve crop WUE, Selection of low beta (less sensitivity to drought) will be difficult, given the yield beta vs. yield correlation (r = 0.71). The major quantitative trait loci (QTL) for yield beta, yield, and CID were coincident with maturity and/or determinancy QTLs. except for a CID QTL in linkage group U09-C2. but it had no effect on beta. Genetic improvement of soybean yield performance under drought would be better achieved by coupling a high-yield grand mean with a high- (not low-) yield beta.

Impact of Bt corn pollen on monarch butterfly populations: A risk assessment

Abstract: A collaborative research effort by scientists in several states and in Canada has produced information to develop a formal risk assessment of the impact of Bt corn on monarch butterfly (Danaus plexippus) populations. Information was sought on the acute toxic effects of Bt corn pollen and the degree to which monarch larvae would be exposed to toxic amounts of Bt pollen on its host plant, the common milkweed, Asclepias syriaca, found in and around cornfields. Expression of Cry proteins, the active toxicant found in Bt corn tissues, differed among hybrids, and especially so in the concentrations found in pollen of different events. In most commercial hybrids, Bt expression in pollen is low, and laboratory and field studies show no acute toxic effects at any pollen density that would be encountered in the field. Other factors mitigating exposure of larvae include the variable and limited overlap between pollen shed and larval activity periods, the fact that only a portion of the monarch population utilizes milkweed stands in and near cornfields, and the current adoption rate of Bt corn at 19% of North American corn-growing areas. This 2-year study suggests that the impact of Bt corn pollen from current commercial hybrids on monarch butterfly populations is negligible.

The Transmission of Marital Instability across Generations: Relationship Skills or Commitment to Marriage?

Abstract: We used national, longitudinal data from 2 generations to assess 2 explanations for the intergenerational transmission of marital instability, one based on relationship skills and the other based on marital commitment. Parental divorce approximately doubled the odds that offspring would see their own marriages end in divorce. Offspring with maritally distressed parents who remained continuously married did not have an elevated risk of divorce. Divorce was most likely to be transmitted across generations if parents reported a low, rather than a high, level of discord prior to marital dissolution. These results, combined with other findings from the study, suggest that offspring with divorced parents have an elevated risk of seeing their own marriages end in divorce because they hold a comparatively weak commitment to the norm of lifelong marriage.

Tropical climate changes at millennial and orbital timescales on the Bolivian Altiplano

Abstract: Tropical South America is one of the three main centres of the global, zonal overturning circulation of the equatorial atmosphere (generally termed the ‘Walker’ circulation1) Although this area plays a key role in global climate cycles, little is known about South American climate history Here we describe sediment cores and down-hole logging results of deep drilling in the Salar de Uyuni, on the Bolivian Altiplano, located in the tropical Andes We demonstrate that during the past 50,000 years the Altiplano underwent important changes in effective moisture at both orbital (20,000-year) and millennial timescales Long-duration wet periods, such as the Last Glacial Maximum—marked in the drill core by continuous deposition of lacustrine sediments—appear to have occurred in phase with summer insolation maxima produced by the Earth's precessional cycle Short-duration, millennial events correlate well with North Atlantic cold events, including Heinrich events 1 and 2, as well as the Younger Dryas episode At both millennial and orbital timescales, cold sea surface temperatures in the high-latitude North Atlantic were coeval with wet conditions in tropical South America, suggesting a common forcing

Marital Happiness, Marital Duration, and the U-Shaped Curve: Evidence from a Five-Wave Panel Study

Abstract: Previous research suggests a U-shaped pattern of marital happiness over the life course, with happiness declining in the early years of marriage and rising in the later years. Mostprior studies have been limited by the use of cross-sectional data or nonprobability samples. In contrast, the present study is based on data from a national, 1 7-year, 5wave panel sample. Using cross-sectional data from the first wave, we replicate the Ushaped relationship between marital happiness and marital duration. In an analysis based on a fixed-effects pooled time-series model with multiple-wave panel data, we find declines in marital happiness at all marital durations and no supportfor an upturn in marital happiness in the later years. The relationship between marital happiness and marital duration is slightly curvilinear, with the steepest declines in marital happiness occurring during the earliest and latest years of marriage. When other lifecourse variables are controlled, a significant negative effect of marital duration on marital happiness remains. For most marriage cohorts, marital happiness declined more in the 1980s than in the 1990s, suggesting a period effect. This study provides evidence that the U-shaped pattern of marital happiness over the life course is an artifact of cross-sectional research and is not typical of U.S. marriages.

Mobile Commerce: Promises, Challenges and Research Agenda

Abstract: Advances in wireless technology increase the number of mobile device users and give pace to the rapid development of e-commerce using these devices. The new type of e-commerce, conducting transactions via mobile terminals, is called mobile commerce. Due to its inherent characteristics such as ubiquity, personalization, flexibility, and dissemination, mobile commerce promises businesses unprecedented market potential, great productivity, and high profitability. This paper presents an overview of mobile commerce development by examining the enabling technologies, the impact of mobile commerce on the business world, and the implications to mobile commerce providers. The paper also provides an agenda for future research in the area.

Use of Remote-Sensing Imagery to Estimate Corn Grain Yield

Abstract: ground-based booms, aircraft, or satellites—is a potentially important source of data for site-specific crop manRemote sensing—the process of acquiring information about obagement, providing spatial and temporal information jects from remote platforms such as ground-based booms, aircraft, or satellites—is a potentially important source of data for site-specific (NRC, 1997). Obtaining temporal information that is crop management, providing both spatial and temporal information. detailed and spatially distributed from other site-specific Our objective was to use remotely sensed imagery to compare differ- crop management methods is difficult and expensive ent vegetation indices as a means of assessing canopy variation and (NRC, 1997). Where available, remotely sensed images its resultant impact on corn (Zea mays L.) grain yield. Treatments show spatial and spectral variations resulting from soil consisted of five N rates and four hybrids, which were grown under and crop characteristics. One potential advantage of irrigation near Shelton, NE on a Hord silt loam in 1997 and 1998. remote-sensing imagery is that it is not limited by samImagery data with 0.5-m spatial resolution were collected from aircraft pling interval or geostatistical interpolation, as has been on several dates during both seasons using a multispectral, four-band implied for grid-sampled soil test data (Moran et al., [blue, green, red, and near-infrared reflectance] digital camera system. 1997). Imagery was imported into a geographical information system (GIS) and then georegistered, converted into reflectance, and used to com- For more than 30 yr, remote sensing has been envipute three vegetation indices. Grain yield for each plot was determined sioned as a valuable source of information for crop at maturity. Results showed that green normalized difference vegeta- management. The pioneering research of Colwell (1956) tion index (GNDVI) values derived from images acquired during showed that infrared aerial photography could be used midgrain filling were the most highly correlated with grain yield; to detect loss of vigor from disease in wheat (Triticum maximum correlations were 0.7 and 0.92 in 1997 and 1998, respectively. aestivum L.) and other small grains. One of the earliest Normalizing GNDVI and grain yield variability within hybrids im- digital remote-sensing analysis procedures developed to proved the correlations in both years, but more dramatic increases identify the vegetation contribution in an image was the were observed in 1997 (0.7 to 0.82) than in 1998 (0.92 to 0.95). This ratio vegetation index (RVI), created by dividing nearsuggested GNDVI acquired during midgrain filling could be used infrared reflectance (NIR) by red reflectance (Jordan, to produce relative yield maps depicting spatial variability in fields,

Increasing Situational Interest in the Classroom

Abstract: This paper explores three ways to increase situational interest in the classroom. Situational interest is defined as temporary interest that arises spontaneously due to environmental factors such as task instructions or an engaging text. We review the history of interest research and summarize recent empirical work. We describe three ways to increase interest based on offering meaningful choices to students, selecting well-organized texts that promote interest, and providing the background knowledge needed to fully understand a topic. We conclude with six specific suggestions for increasing situational interest in the classroom.

Abrogation of disease development in plants expressing animal antiapoptotic genes.

Abstract: An emerging topic in plant biology is whether plants display analogous elements of mammalian programmed cell death during development and defense against pathogen attack. In many plant–pathogen interactions, plant cell death occurs in both susceptible and resistant host responses. For example, specific recognition responses in plants trigger formation of the hypersensitive response and activation of host defense mechanisms, resulting in restriction of pathogen growth and disease development. Several studies indicate that cell death during hypersensitive response involves activation of a plant-encoded pathway for cell death. Many susceptible interactions also result in host cell death, although it is not clear how or if the host participates in this response. We have generated transgenic tobacco plants to express animal genes that negatively regulate apoptosis. Plants expressing human Bcl-2 and Bcl-xl, nematode CED-9, or baculovirus Op-IAP transgenes conferred heritable resistance to several necrotrophic fungal pathogens, suggesting that disease development required host–cell death pathways. In addition, the transgenic tobacco plants displayed resistance to a necrogenic virus. Transgenic tobacco harboring Bcl-xl with a loss-of-function mutation did not protect against pathogen challenge. We also show that discrete DNA fragmentation (laddering) occurred in susceptible tobacco during fungal infection, but does not occur in transgenic-resistant plants. Our data indicate that in compatible plant–pathogen interactions apoptosis-like programmed cell death occurs. Further, these animal antiapoptotic genes function in plants and should be useful to delineate resistance pathways. These genes also have the potential to generate effective disease resistance in economically important crops.

Incorporating varying test costs and fault severities into test case prioritization

Abstract: Test case prioritization techniques schedule test cases for regression testing in an order that increases their ability to meet some performance goal. One performance goal, rate of fault detection, measures how quickly faults are detected within the testing process. In previous work (S. Elbaum et al., 2000; G. Rothermel et al., 1999), we provided a metric, APFD, for measuring rate of fault detection, and techniques for prioritizing test cases to improve APFD, and reported the results of experiments using those techniques. This metric and these techniques, however, applied only in cases in which test costs and fault severity are uniform. We present a new metric for assessing the rate of fault detection of prioritized test cases that incorporates varying test case and fault costs. We present the results of a case study illustrating the application of the metric. This study raises several practical questions that might arise in applying test case prioritization; we discuss how practitioners could go about answering these questions.

The relationships among root and leaf traits of 76 grassland species and relative abundance along fertility and disturbance gradients

Abstract: For 76 annual, biennial, and perennial species common in the grasslands of central Minnesota, USA, we determined the patterns of correlations among seven organ-level traits (specific leaf area, leaf thickness, leaf tissue density, leaf angle, specific root length, average fine root diameter, and fine root tissue density) and their relationships with two traits relating to growth form (whether species existed for part of the growing season in basal, non-caulescent form and whether species were rhizomatous or not). The first correlation of traits showed that grasses had thin, dense leaves and thin roots while forbs had thick, low-density leaves and thick roots without any significant differences in growth form or life history. The second correlation of traits showed a gradient of species from those with high-density roots and high-density erect leaves to species with low-density roots and low-density leaves that were held parallel to the ground. High tissue density species were more likely to exist as a basal rosette for part of the season, were less likely to be rhizomatous, and less likely to be annuals. We examined the relationships between the two axes that represent the correlations of traits and previously collected data on the relative abundance of species across gradients of nitrogen addition and disturbance. Grasses were generally more abundant than forbs and the relative abundance of grasses and forbs did not change with increasing nitrogen addition or soil disturbance. High tissue density species became less common as fertility and disturbance increased.

Three positive fixed points of nonlinear operators on ordered banach spaces

Abstract: We generalize the fixed-point theorem of Leggett-Williams, which is a theorem giving conditions that imply the existence of three fixed points of an operator defined on a cone in a Banach space. We then show how to apply our theorem to prove the existence of three positive solutions to a second-order discrete boundary value problem.

Fungal symbiosis from mutualism to parasitism: who controls the outcome, host or invader?

Abstract: Summary • Plant symbiotic fungi are generally thought to express a single lifestyle that might increase (mutualism), decrease (parasitism), or have no influence (commensalism) on host fitness. However, data are presented here demonstrating that plant pathogenic Colletotrichum species are able to asymptomatically colonize plants and express nonpathogenic lifestyles. • Experiments were conducted in growth chambers and plant colonization was assessed by emergence of fungi from surface sterilized plant tissues. Expression of symbiotic lifestyles was assessed by monitoring the ability of fungi to confer disease resistance, drought tolerance and growth enhancement. • Several pathogenic Colletotrichum species expressed either mutualistic or commensal lifestyles in plants not known to be hosts. Mutualists conferred disease resistance, drought tolerance, and/or growth enhancement to host plants. Lifestylealtered mutants expressing nonpathogenic lifestyles had greater host ranges than the parental wildtype isolate. Successive colonization studies indicated that the ability of a symbiont to colonize a plant was dependent on previous colonization events and the lifestyles expressed by the initial colonizing fungus. • The results indicate that the outcome of symbiosis is controlled by the plant’s physiology.

An evaluation of the Standardized Precipitation Index, the China-Z Index and the statistical Z-Score

Abstract: The Standardized Precipitation Index (SPI) was developed to detect drought and wet periods at different time scales, an important characteristic that is not accomplished with typical drought indices. More and more users employ the SPI to monitor droughts. Although calculation of the SPI is easier than other drought indices, such as the Palmer Drought Index, it is still relatively complex. In China, an index called the China-Z Index (CZI) has been used since 1995 by the National Climate Centre of China to monitor moisture conditions across the country. The calculation of this index is easier than the SPI. A third index, the statistical Z-Score, can also be used to monitor droughts. This paper evaluates the SPI, CZI and Z-Score on 1-, 3-, 6-, 9- and 12-month time scales using monthly precipitation totals for four locations in China from January 1951 to December 1998 representing humid and arid climates, and cases of drought and flood. Advantages and disadvantages for the application of each index are compared. Study results indicate that the CZI and Z-Score can provide results similar to the SPI for all time scales, and that the calculations of the CZI and Z-Score are relatively easy compared with the SPI, possibly offering better tools to monitor moisture conditions. Copyright © 2001 Royal Meteorological Society