Polynomial Regression Analysis Research Articles

Use of an Artificial Neural Network for Tensile Strength Prediction of Nano Titanium Dioxide Coated Cotton.

In this study, an artificial neural network (ANN) is used for the prediction of tensile strength of nano titanium dioxide (TiO2) coated cotton. The coating process was performed by ultraviolet (UV) radiations. Later on, a backpropagation ANN algorithm trained with Bayesian regularization was applied to predict the tensile strength. For a comparative study, ANN results were compared with traditional methods including multiple linear regression (MLR) and polynomial regression analysis (PRA). The input conditions for the experiment were dosage of TiO2, UV irradiation time and temperature of the system. Simulation results elucidated that ANN model provides high performance accuracy than MLR and PRA. In addition, statistical analysis was also performed to check the significance of this study. The results show a strong correlation between predicted and measured tensile strength of nano TiO-coated cotton with small error values.

Resistance spot welding of advanced high strength steel for fabrication of thin-walled automotive structural frames

This investigation presents the process parameter optimization of resistance spot welded (RSW) advanced high strength steel (AHSS) joints using response surface methodology (RSM) for fabrication of thin-walled automotive structural frames. Resistance spot welding (RSW) is used to minimize solidification cracking, heat affected zone (HAZ) softening and distortion related problems in joining of thin advanced high strength steel (AHSS) sheets. The three factor – five level central composite design (3 × 5 - CCD) matrix pertaining to the minimum number of experiments was chosen for designing the experimental matrix. The polynomial regression analysis was employed to develop the empirical relationships between RSW parameters and performance characteristics of AHSS joints. The 3-dimensional (3D) response surfaces were developed using RSM which shows the optimal process window to enhance the strength of spot joints. The RSW joints made using welding current of 5.0 kA, electrode pressure of 4.0 MPa, and welding time of 1.50 s displayed maximum lap tensile shear fracture load (LAP-TSFL) of 21.7 kN, cross tensile shear fracture load (CROSS-TSFL) of 17.65 kN, and nugget zone hardness (NZH) of 589 HV0.5 respectively. The results of ANOVA indicates that welding current, electrode pressure and welding time significantly influences the LAP-TSFL, CROSS-TSFL and NZH of joints respectively. The superior TSFL and NZH of joints made using optimized RSW parameters is attributed to the evolution of needle/lath martensite in nugget zone .

Impact of Customer Compensation Strategies on Outcomes and the Mediating Role of Justice Perceptions: A Longitudinal Study of Target’s Data Breach

Data breaches are a major threat to organizations from both financial and customer relations perspectives. We developed a nomological network linking post-breach compensation strategies to key outcomes, namely continued shopping intentions, positive word-of-mouth, and online complaining, with the effects being mediated by customers’ justice perceptions. We conducted a longitudinal field study investigating Target’s data breach in 2013 that affected more than 110 million customers. We examined customers’ expectations toward compensation immediately after the breach was confirmed (survey 1) and their experiences after reparations were made (survey 2). Evidence from polynomial regression and response surface analyses of data collected from 388 affected customers showed that customers’ justice perceptions were influenced by the actual compensation provided as well as the type and extent of compensation an organization could and should have provided (i.e., customers’ compensation expectations). Interestingly, both positive and negative expectation disconfirmation led to less favorable justice perceptions compared to when expectations were met. Justice perceptions were, in turn, associated with key outcomes. We discuss implications for research on data security, information systems, and justice theory.

No aspect of structure should be left behind in relation to student autonomous motivation.

Provision of structure in classroom settings constitutes one of the pillars of conducive learning environments. However, little is known whether the particular elements of provided structure-namely, contingency, clear expectations, help and support, and monitoring-are equally important for student learning and motivation. In this cross-sectional study, we aimed to investigate to what extent students' autonomous motivation is linearly and curvilinearly related to their perceptions of their teachers' contingency, clear expectations, help and support, and monitoring. Participants were 12,036 Turkish adolescent students (age range: 15-19 years; 54.4% males) from 446 classes, nested into 24 public schools. Cross-sectional, based on student ratings of their self-determined motivation and their teacher structure provision and autonomy support. Multilevel and ordinary least-squares polynomial regression analyses showed all the four perceived structure elements to predict autonomous motivation, with expectations and contingency (especially when coupled with monitoring) being even more important predictors than the other elements. Response surface analyses also showed strong positive relation between autonomous motivation and all the possible pairs of the four elements of perceived structure along the line of congruence, suggesting an additive effect when teachers are thought to be contingent and helpful and supportive (or monitor their students, or clearly communicate their expectations). These findings imply the key role that teachers could play in enhancing their students' autonomous motivation by providing all the elements of structure.

From Speculation to Substantiation: Empirically-Testing Societal Changes in Impact of Fit on Job Satisfaction from 1989, 1998, 2006, and 2016

Against the backdrop of large-scale changes in work over the past few decades, both business leaders and academics have speculated that employees’ job satisfaction is increasingly tied to the extent to which their jobs meet their desires for meaning and other reinforcers. However, empirical evidence has not yet been brought to bear on these arguments. In order to provide insights into potential socio-temporal changes in how employees derive job satisfaction from job characteristics, we analyzed repeated large-scale population surveys in the United States to examine the impact of fit between desiring and receiving job characteristics on job satisfaction across four time points (1989, 1998, 2006, and 2016). Moderated polynomial regression analyses indicated that employees in more recent years experience greater dissatisfaction by deficiencies in intrinsically-rewarding job characteristics. We interpret these findings against broader discussions of the changing employment narrative theorized to have occurred in the United States over the past several decades.

Effects of Dietary Carbohydrate Levels on the Growth and Glucose Metabolism of Juvenile Swimming Crab, Portunus trituberculatus

This experiment was conducted to evaluate the effects of different carbohydrate levels on the growth performance, glycogen accumulation in tissue, enzyme activities, and expression levels of genes related to hepatopancreatic glucose and lipid metabolism and insulin signaling pathway in swimming crab, Portunus trituberculatus for 8 weeks. The results indicated that crabs fed with the 60.0 g kg-1 carbohydrate diet exhibited the highest final body weight (FBW), percent weight gain (PWG), and specific growth rate (SGR) among all treatments. FBW, PWG, and SGR significantly decreased when dietary carbohydrate levels exceeded 240.0 g kg-1. Light microscopy results showed that dietary excessive carbohydrate levels will lead to vacuole, hepatopancreatic tubule lysis, and lipid droplets in hepatopancreas. Expression levels of genes involved into glucose transport, glucose and lipid metabolism, and insulin-like metabolism in the hepatopancreas were significantly influenced by dietary carbohydrate levels. In general, the results of present study demonstrated that dietary optimal carbohydrate levels could not only improve PWG and SGR but also influence the expression of genes involved in glucose, lipid, and insulin-like metabolism. The optimal actual carbohydrate level was estimated to be 87.8-98.4 g kg-1 based on broken-line and second-order polynomial regression analysis between PWG against dietary carbohydrate levels for juvenile Portunus trituberculatus.

Phenotype of higher post-load insulin response as a predictor of all-cause mortality and cardiovascular mortality in the Chinese non-diabetic population

AimThis study aimed to assess whether a higher insulin response increased the long-term risk of mortality in a non-diabetic population.MethodsA total of 446 people with normal glucose tolerance (NGT) or impaired glucose tolerance (IGT) who participated in the Da Qing Diabetes Study, were stratified into quartiles subgroups according to their baseline insulin area under the curve (AUC) during oral glucose tolerance test, defined as Q1, Q2, Q3 and Q4. The participants were followed from 1986 to 2016 to assess the risk of death in association with the magnitude of post-load insulin response.ResultsOver 30 years, the rates of all cause death were 9.94, 14.81, 15.02, and 17.58 per 1000 person-years across the four groups respectively. The rate for cardiovascular disease (CVD) death was 5.14, 6.50, 6.80 and 10.47 per 1000 person-years. Compared with Q1, the risk of all-cause death was significantly higher in participants in Q4 (HR = 2.14, 95% CI 1.34–3.42), Q3 (HR = 1.94, 95% CI 1.20–3.14), and Q2 group (HR = 1.70, 95% CI 1.06–2.74). In the Fine-Gray model with non-CVD death as competing risk, the increased insulin AUC were also significantly associated with the CVD death (Q4 vs Q1, HR = 2.04, 95% CI 1.10–3.79). In the fractional polynomial regression analysis, a nonlinear association between insulin AUC and all-cause and CVD death was demonstrated. In addition, insulin AUC was associated with a progressively higher risk of all-cause death and CVD death (fractional power 3, P < 0.001).ConclusionA higher post-load insulin response was significantly associated with a long-term increased risk of all-cause and CVD deaths in the Chinese non-diabetic population. It suggests that people featured by this phenotype is a potential important target for further intervention.

Optimal Fertilization Level for Yield, Biological and Quality Traits of Soybean under Drip Irrigation System in the Arid Region of Northwest China

Soybean is one of the most important oilseed crops worldwide. Fertilization severely restricts the yield potential of soybean in the arid regions of Northwest China. A two-year field experiment was conducted to investigate the effects of fertilization on soybean yield in arid areas under a drip irrigation system. The treatment consisted of 14 fertilizer combinations comprising of four rates each of nitrogen (N) (0, 225, 450, and 675 kg ha−1), phosphorus (P) (0, 135, 270, and 405 kg ha−1), and potassium (K) (0, 75, 150, and 225 kg ha−1). The results revealed that grain yield was more sensitive to N fertilizer than to P and K fertilizers. The P and K fertilizers influenced harvest index and biomass, respectively. The optimized combination of fertilizers for high yield, as well as biological and quality traits was obtained by quadratic polynomial regression analysis. The theoretical grain yields based on the performed statistical calculations and plant biomass were greater than 7.21 tons ha−1 and 16.38 tons ha−1 with 300,000 plants ha−1 and were obtained under a fertilization combination of 411.62–418.39 kg ha−1 N, 153.97−251.03 kg ha−1 P2O5, and 117.77−144.73 kg ha−1 K2O. Thus, our findings will serve as a guideline for an effective fertilizer application in order to achieve a balance between grain yield and plant biomass as well as to contribute to the promotion of large-scale cultivation of soybean under drip irrigation.

Polynomial regression analysis and response surface methodology in leadership research

Congruence has served as an important research framework for many leadership research topics. Perhaps the most frequently used methodological/statistical approach for testing the congruence framework is polynomial regression analysis (PRA) with response surface methodology (RSM). As this approach was introduced to organizational sciences more than two decades ago, we can now identify the main issues with the use of this approach in leadership research. To systematically investigate these issues, we first review how PRA and RSM have been used in various leadership studies. We then review the levels-of-analysis and rater model assumptions prevalent in PRA in terms of multilevel techniques, choice of centering options, and issues of endogeneity. Finally, to better understand the inconsistencies and variabilities that exist in leadership research, we review the use of two main RSM features and summarize additional statistical techniques for assessment in this realm. Overall, we aim to promote the rigorousness of this methodology within the study of congruence in leadership research by enhancing its capability in theory testing and building.

Association of Bolus Transit Time on Barium Esophagram With Esophageal Peristalsis on High-resolution Manometry and Nonobstructive Dysphagia.

The goal of this study was to correlate upright and prone bolus transit time (BTT) on barium esophagography (BE) with esophageal peristalsis on high-resolution manometry (HRM) and self-reported dysphagia in patients with normal lower esophageal sphincter parameters on HRM. BTT on BE could be the gold standard for assessing the effectiveness of esophageal peristalsis if it can be quantified. Patients with normal lower esophageal sphincter parameters and standard-protocol BE from 2017 to 2020 were included. Patients were divided, based on the number of normal swallows (distal contractile integral >450 mm Hg-s-cm), into 11 groups (10 normal swallows to 0 normal swallows). Liquid barium swallows in prone position were objectively evaluated for prone BTT. Patients reported difficulty in swallowing on a scale from 0 (none) to 4 (very severe). Fractional polynomial and logistic regression analysis were used to study the association (along with the rate of change) between BTT, peristalsis, and dysphagia. A total of 146 patients were included. Prone BTT increased as the number of normal swallows decreased ( P <0.001). Two deflection points were noted on the association between peristalsis and prone BTT at 50% normal swallows, 40 seconds and 30% normal swallows, 80 seconds, after which peristaltic function declined independently of prone BTT. Patients with prone BTT>40 seconds had nearly 6-fold higher odds of 0% normal swallows on HRM than patients with prone BTT<40 seconds ( P =0.002). Increasing prone BTT was associated with increasing dysphagia grades 1 and 2 ( P ≤0.036). Esophageal motility can be quantified by BE. Prone BTT correlates with the proportion of normal esophageal swallows and dysphagia.

Interactive effects of level of nitrogen and irrigation application on maize yield

Maize (Zea mays L.) yields are recognized to be sensitive to both the level of nitrogen fertilization and irrigation that is applied to the crop. However, there are virtually no studies where experimental results are analyzed to quantitatively explore directly the interactive influence of these two resources on yield. As a consequence, it is difficult to sort out the optimum management regime for the available resources. A polynomial regression analysis was applied to results from seven field experiments involving several nitrogen and irrigation treatments. The polynomial equation included for each resource a linear term and second-order term plus a multiplicative term of the two resources. The polynomial regression fit very well the results of all experiments (R2 ≥ 0.86). The impact of irrigation included the linear term in all experiments (p ≤ 0.017). In all but one experiment, yield was also linearly dependent on amount of nitrogen application. The polynomial expression led to determination of the nitrogen fertilization required for maximum yield as being dependent on level of irrigation. In all cases, increased irrigation amounts resulted in an increased nitrogen requirement to achieve maximum yield. Another important outcome of the analysis was that the multiplicative term for irrigation x nitrogen was generally important in describing yield. These results demonstrate the inadequacy of attempting to define the results of such multiple-factor experiments based on a single limiting-factor approach.

Estimating the Postmortem Interval of Carcasses in the Water Using the Carrion Insect, Brain Tissue RNA, Bacterial Biofilm, and Algae.

The accurate estimation of postmortem interval (PMI) is crucial in the investigation of homicide cases. Unlike carcasses on land, various biological and abiotic factors affect the decomposition of carcasses in water. In addition, the insect evidence (e.g., blow flies) that is commonly used to estimate the PMI are unavailable before the carcasses float on water. Therefore, it is difficult to estimate the PMI of a carcass in water. This study aimed to explore an effective way of estimating the PMI of a carcass in water. Carrion insects, brain tissue RNA, bacterial biofilm on the skin surface, and algae in water with PMI were studied using 45 rat carcasses in a small river. The results showed that carrion insects might not be suitable for the estimation of PMI of a carcass in water since they do not have a regular succession pattern as a carcass on land, and the flies only colonized six of the carcasses. The target genes (β-actin, GAPDH, and 18S) in the brain tissue were associated with the PMI in a time-dependent manner within 1 week after death. A polynomial regression analysis was used to assess the relationship between the gene expression profiles and PMI. The correlation coefficient R2 of each regression equation was ≥ 0.924. A third-generation sequencing analysis showed that the bacteria on the skin surface of the carcass and the algae in the water samples around the carcass had a regular succession pattern, where Cryptomonas and Placoneis incased and decreased, respectively, within first 9 days. The results of this study provide a promising way to use the brain tissue RNA, bacterial biofilm, and algae to estimate the PMI of a carcass in water.

New insights in travel satisfaction research

Transit users’ travel satisfaction is important for assessing the performance of transit-oriented development. Existing studies emphasize the role of service attributes, built environment, and travel attitudes in predicting transit users’ travel satisfaction. However, few studies have jointly examined the effects of environment and attitudes based on sophisticated theoretical foundations. This paper aims to narrow this gap by examining the interaction effects of transit accessibility and attitudes towards transit on transit users' travel satisfaction from a person-environment fit perspective. The data is from a household survey conducted in Shanghai in 2018. Using polynomial regression analysis with response surface methodology, the study finds that interaction effects significantly influence the affective component of travel satisfaction, but not the cognitive component. Public transit users’ travel satisfaction increases with the congruence between attitude and accessibility. Dissonance is not necessarily a bad situation and may improve travel satisfaction when there is an increase in either factor.

Evaluation of Correlation Between Surface Diaphragm Electromyography and Airflow Using Fixed Sample Entropy in Healthy Subjects.

In clinic, the acquisition of airflow with nasal prongs, masks, thermistor to monitor respiratory function is more uncomfortable and inconvenience than surface diaphragm electromyography (EMGdi) using electrode pads. The EMGdi with strong electrocardiograph (ECG) interference affect the extraction of its characteristic information. In this work, surface EMGdi and airflow signals of 20 subjects were collected under 5 incremental inspiratory threshold loading protocols from quiet breathing to maximum forced breathing. First, we filtered out the ECG interference in EMGdi based on the combination of stationary wavelet transform and the positioning of ECG to obtain pure EMGdi (EMGdip). Second, the Spearman's rank correlation coefficients between EMGdi and EMGdip quantified by time series fixed sample entropy (fSampEn), root mean square (RMS), and envelope were compared to verify the robustness of the fSampEn to ECG. A comparative analysis of correlation between fSampEn of EMGdi and inspiratory airflow and the correlation between envelope of EMGdip (EMGdie) and inspiratory airflow found that there was no significant difference between the two, indicating the feasibility of using fSampEn to predict airflow. Moreover, fSampEn of EMGdi was used as characteristic parameter to build a quantitative relationship with the airflow by polynomial regression analysis. Mean coefficient of determination of all subjects in any breathing state is greater than 0.88. Finally, nonlinear programming method was used to solve a universal fitting coefficient between fSampEn of EMGdi and airflow for each subject to further evaluate the possibility of using surface EMGdi to monitor and control respiratory activity.

The Influence of the Matching of Leader’s Authorization Behavior and Employee’s Authorization Expectation on Employee’s Active Behavior: Based on the Theory of Personal-Environmental Matching

Purpose: Based on the theory of personal-environment matching, from the perspective of matching a leader’s authorization behavior with an employee’s authorization expectation, this paper explores the question of when the authorization utility is maximized. Design/Methodology/Approach: Polynomial regression and response surface analysis were used to analyze the two-stage matching data of 45 leaders and 303 subordinates. Findings: It is found that when the leader’s authorization behavior and the employee’s authorization expectation are in “high-high” agreement, the employee’s harmonious work passion and positive behavior are the highest, and harmonious work passion plays an intermediary role between the leader’s authorization behavior and employee’s authorization expectation and employee’s positive behavior. Practical Implications: The findings provide a helpful reference for management practitioners on how to authorize better, stimulate employees’ harmonious work passion, and promote employees’ positive behaviors. Originality/Value: First, from the dual perspective of leaders and subordinates, comprehensively and dialectically analyzes how to maximize the effectiveness of authorization. Second, from the standpoint of positive emotion cognition, the emotional driving mechanism of an employee’s positive behavior is demonstrated by matching the leader’s authorized behavior with the employee’s authorized expectations.

Changes in client attachment in relation to client distress: A response surface analysis.

Using multilevel polynomial regression and response surface analysis, we studied the association between Time 1 (T) and Time 2 (T + 1) attachment anxiety and attachment avoidance, and T + 1 psychological distress in 253 nine-session time periods for 65 adult community clients working with 13 doctoral student therapists in open-ended psychodynamic psychotherapy. Results indicated that when client attachment anxiety was consistent and higher from the beginning (T) to the end (T + 1) of a nine-session time period, clients tended to report higher distress at the end of the period; when attachment anxiety was consistent and lower across a time period, clients tended to report lower distress. When attachment anxiety decreased across a time period, clients reported lower distress at the end of the period; when attachment anxiety increased across a time period, clients reported higher distress. Neither within-client consistency nor change in attachment avoidance in a time period was significantly related to client distress at the end of the period. Limitations and implications of the present research are discussed. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

HIV/AIDS and the social determinants of health: a time series study.

To analyze the time trend, spatial distribution, and the cases of human immunodeficiency virus/acquired immunodeficiency syndrome cases with social determinants of health. Ecological and analytical study, carried out based on the cases of human immunodeficiency virus/acquired immunodeficiency syndrome notified in a state in the Brazilian Midwest, from 2009 to 2018. The study used descriptive analysis, polynomial regression, and geospatial analysis. In 10 years, there were 9,157 notifications, growing each year. There was a growing trend for both sexes (p<0.001, r2=0.94). The City Human Development Index was related to the higher number of cases (city of notification, p=0.01; and city where the person lives, p=0.02). The highest concentration was in cities that house health macro-regions. Social determinants have a relationship with the time trend and the spatial distribution of cases and can direct strategies for prevention and care.

Dietary Incorporation of Bacillus subtilis and Bacillus licheniformis Mixture (DiPro Aqua) Ameliorates Growth Performance, Immune Response, and Intestinal Morphology in Rainbow Trout

AbstractThe current study was designed to investigate the role of a commercial probiotic containing equal proportions (1:1) of Bacillus subtilis and B. licheniformis spores (1.6 × 1012 CFU/kg; DiPro Aqua) on the growth, immune response, and intestinal morphology of Rainbow Trout Oncorhynchus mykiss. A total of 168 Rainbow Trout fry were randomly divided into four groups and were fed diets with different doses of DiPro Aqua (control: 0 CFU/kg; treatment 1 [T1]: 8 × 108 CFU/kg; T2: 16 × 108 CFU/kg; T3: 24 × 108 CFU/kg) for 56 d. The highest body weight gain and specific growth rate were obtained in the T2 and T3 groups. In addition, the highest feed conversion ratio was measured in the control group. The results showed that the serum total immunoglobulins and total protein content were increased in fish that were fed the T2 and T3 diets compared to those that received the T1 and control diets (P &lt; 0.05). The highest alternative complement pathway hemolytic activity was measured in T2 fish compared to the other groups. According to the antibacterial activity of the skin mucus samples against Yersinia ruckeri, dietary levels of DiPro Aqua improved the mucus bactericidal activity and the maximum effect was recorded in the T2 group. The dietary levels of the probiotic mixture, especially in T2, increased the villus length, villus width, and crypt depth within the distal intestine compared to those in the control group. In conclusion, the optimal dietary dose of DiPro Aqua to boost growth performance, immunity, and intestinal morphology in Rainbow Trout was 2.0 × 108 CFU/kg based on polynomial regression analysis.

The effect of different dietary protein levels on growth performance and nutrient utilization of snarpsnout sea bream ( Diplodus puntazzo )

This study evaluated the effects of different dietary protein levels on growth performance and nutrient utilization of snarpsnout sea bream (Diplodus puntazzo) juveniles. Five isoenergetic diets were formulated to contain a dietary protein level at 30% (P30), 35% (P35), 40% (P40), 45% (P45) and 50% (P50). Each diet was randomly assigned to triplicate groups of fish (IBW 2.80 g) and fed to apparent satiation for 100 days. The dietary protein to energy ratio significantly affected the feed intake with the lower ratios leading to a higher feed consumption. The growth performance of D. puntazzo was gradually increased as the dietary protein level increased up to 40% and then gradually reduced as the dietary protein increased further to 45% and 50%. The feed efficiency got improved as dietary protein levels increased up to 45% but slightly decreased at 50% protein level. A second-degree polynomial regression analysis estimated that a dietary protein level at 41.4% and 43.8% delivered the maximum weight gain and the higher feed efficiency, respectively. The increased dietary carbohydrate and lipid levels in fish fed a low protein diet (P30) resulted in a significant deterioration of feed conversion and growth rates showing also reduced nutrient retentions and causing severe mortalities.

Spatiotemporal Patterns of Leymus arenarius Nebkhas during Early Primary Succession on the Sub-Arctic Coastal Sand Plains of Iceland

Greipsson, S., 2022. Spatiotemporal patterns of Leymus arenarius nebkhas during early primary succession on the subArctic coastal sand plains of Iceland. Journal of Coastal Research, 38(2), 269–278. Coconut Creek (Florida), ISSN 0749-0208. A spatiotemporal analysis of phytogenic mounds (nebkhas) of the pioneer dune building grass Leymus arenarius was assessed during primary succession on three coastal sand plains in Iceland. Extensive sand plains were formed on the study sites due to catastrophic glacial river floods associated with sub-glacial volcanic activities. Present and past spatial patterns of Leymus-nebkhas were examined by the use of satellite images and high resolution aerial photographs and confirmation through field work. The colonization patterns of the nebkhas were studied from the initial phases and up to a maximum period of 54 years on the sand plains Skeidararsandur, Myrdalssandur, and Skogarsandur. The hypothesis was that nebkhas would be clustered and nonrandom in early phases of the primary succession but would have random configurations at later stages. Average density of nebkhas was low within 10 years of colonization on Skeidararsandur (0.55–0.67 dunes ha–1) and the spatial configuration was found to be highly nonrandom (clumped). Following the initial colonization of L. arenarius, the increase of nebkha density with time followed a similar nonrandom pattern on Myrdalssandur with final average density of 6.12 nebkha ha–1. On Skogarsandur, the spatial configuration of nebkhas was random with final average density of 7.08 nebkha ha–1. Nonlinear cubic polynomial regression analysis showed a very strong relationship (R2 = 0.989) for the average density of nebkha for 60 years on Skogarsandur. On the coastal sand plains, the spatial configuration of nebkha was observed to progress with time from nonrandom towards random distribution. This study supports the view of deterministic spatiotemporal pattern of nebkhas during early primary succession on the coastal sand plains. The nebkha density was most likely a function of sand drift on the plains, significantly decreasing (R2 = 0.93) away from the sand source of the glacier river Jökulsa on Skogarsandur. The results are discussed in relation to ecological restoration.