Robustness of zero-augmented models over generalized linear models in analysing fertility data in Nigeria.

OBJECTIVE: Fertility is a count data usually rightly skewed and exhibiting large number of zeros than the distributional assumption of the generalized linear models (GLMs). This study examined the robustness of zero-augmented models over GLMs to fit fertility data across regions in Nigeria. The 2013 Nigeria Demographic and Health Survey data were used. The fertility models fitted included: Poisson, negative binomial, zero-inflated Poisson, zero-inflated negative binomial, hurdle Poisson and hurdle negative binomial. Akaike Information Criteria (AIC) and Bayesian Information Criteria (BIC) were used to identify the model with best fit (α = 0.05). RESULTS: The percentage of zero count in the fertility responses were 21.3, 23.9, 31.1, 30.7, 37.6 and 42.4 in North West, North East, North Central, South West, South South and South East regions respectively. In all the six regions in Nigeria, the zero-augmented models were better than the generalized linear models except for North Central. Extensively, the zero-augmented negative binomial based models were of better fit than their Poisson based counterparts; or in rare cases maybe indistinguishable. However, specific family of zero-augmented model is recommended for each region in Nigeria.

School Refusal Behavior in Indian Children: Analysis of Clinical Profile, Psychopathology and Development of a Best-Fit Risk Assessment Model.

OBJECTIVES: School refusal is seen as an emergency in child psychiatry and various risk factors have been analyzed. Children who present with school refusal have been shown to have several associated psychiatric comorbidities. However, risk assessment of psychiatric comorbidities is lacking, particularly in the Indian context. The authors aimed to study the sociodemographic profile and associated psychopathology in children with school refusal. They compared the prevalence rates of psychiatric illnesses to that of the community. A best-fit model for risk assessment of psychopathology was formulated. METHODS: Past records of children aged 5-16 y, who presented with school refusal in the period from June 2013 through June 2015 to authors' Child Guidance Clinic were studied and their sociodemographic details, symptoms and diagnoses were obtained. Chi square test of proportion was used to compare the prevalence rates between the study population and community. Multinomial analysis was used to elucidate a best-fit model of risk assessment. RESULTS: School refusal was seen in 3.6% of children. 77.8% of the children had a psychiatric diagnosis, most common being depression (26.7%), followed by anxiety (17.7%). Prevalence of psychiatric disorders was significantly higher in the study population than community (p < 0.05). A best-fit model of 4 factors: academic difficulties, adjustment problems at school, behavioral problems and parental conflicts is suggested (p < 0.05). CONCLUSIONS: School refusal is associated with significant psychopathology, most commonly depression, followed by anxiety. The best-fit model for risk assessment can predict the likelihood of psychopathology and help in early diagnosis.

Relationship between epistasis and aggressiveness in resistance of pepper (Capsicum annuum L.) to Phytophthora nicotianae.

This study evaluated the types of gene action governing the inheritance of resistance to Phytophthora nicotianae necrosis in populations derived from two crosses involving two susceptible (Beldi and Nabeul II) and one resistant (CM334) cultivars of pepper (Capsicum annuum L.). Populations, composed of Pr, Ps, F(1) , F (2) , BC (1) Pr, and BC (1) Ps generations, were inoculated with six P. nicotianae isolates. Generation means analysis indicated that an additive-dominance model was appropriate for P. nicotianae isolates Pn (Ko1) , Pn (Ko2) and Pn (Kr1) , which showed low aggressiveness in the two crosses. For the more aggressive isolates Pn (Bz1) , Pn (Bz2) and Pn (Kr2) , epistasis was an integral component of resistance in the two crosses. The presence of epistasis in the resistance of pepper to P. nicotianae was dependent on the level of aggressiveness of the isolates. Selection in pepper with less aggressive isolates was efficient, but not with more aggressive isolates; on the other hand, selection with more aggressive isolates was more stable. The minimum number of genes controlling resistance was estimated at up to 2.71. In the majority of cases, the additive variance was significant and greater than the environmental and dominance variance.

Relationship between epistasis and aggressiveness in resistance of pepper (Capsicum annuum L. ) to Phytophthora nicotianae

This study evaluated the types of gene action governing the inheritance of resistance to Phytophthora nicotianae necrosis in populations derived from two crosses involving two susceptible (Beldi and Nabeul II) and one resistant (CM334) cultivars of pepper (Capsicum annuum L.). Populations, composed of Pr, Ps, F1,F2,BC1Pr, and BC1Ps generations, were inoculated with six P. nicotianae isolates. Generation means analysis indicated that an additive-dominance model was appropriate for P. nicotianae isolates PnKo1,PnKo2 and PnKr1, which showed low aggressiveness in the two crosses. For the more aggressive isolates PnBz1,PnBz2 and PnKr2, epistasis was an integral component of resistance in the two crosses. The presence of epistasis in the resistance of pepper to P. nicotianae was dependent on the level of aggressiveness of the isolates. Selection in pepper with less aggressive isolates was efficient, but not with more aggressive isolates; on the other hand, selection with more aggressive isolates was more stable. The minimum number of genes controlling resistance was estimated at up to 2.71. In the majority of cases, the additive variance was significant and greater than the environmental and dominance variance.