Auxiliary Character Research Articles

The Brazilian Goblin Spiders of the New Genus Predatoroonops (Araneae: Oonopidae)

The new endemic goblin spider genus Predatoroonops is erected for 17 new soft-bodied oonopid species from Brazil: Predatoroonops schwarzeneggeri, sp. nov., is the type species of the genus, P. poncho, sp. nov., P. billy, sp. nov., P. valverde, sp. nov., P. blain, sp. nov., P. maceliot, sp. nov., P. anna, sp. nov., P. rickhawkins, sp. nov., P. dutch, sp. nov., P. dillon, sp. nov., P. vallarta, sp. nov., P. phillips, sp. nov., P. yautja, sp. nov., P. peterharlli, sp. nov., P. mctiernani, sp. nov., P. chicano, sp. nov., and P. olddemon, sp. nov. Males of this new genus are easily diagnosed and separated from other Oonopinae genera by the extremely modified male chelicerae that frontally have median furrows and accentuated projections. The females can be recognized by the genitalia, which have a conspicuous posterior receptaculum, usually exposed between the epigastric folds. An auxiliary character for both sexes could be the presence of very long pairs of ventral spines with pronounced bases on the legs I and II tibiae and metatarsi. The genus is considered endemic and the species are recorded mainly from the Brazilian Atlantic Forest. An identification key is provided for all Predatoroonops species known to date.

Estimation of finite population mean in two-phase sampling with known coefficient of variation of an auxiliary character

In this paper a double (or two-phase) sampling version of (Singh and Tailor, 2005) estimator has been suggested along with its properties under large sample approximation. It is shown that the estimator due to (Kawathekar and Ajgaonkar, 1984) is a member of the proposed class of estimators. Realistic conditions have been obtained under which the proposed estimator is better than usual unbiased estimator, usual double sampling ratio ( tRd ) product ( tPd ) estimators and (Kawathekar and Ajgaonkar, 1984) estimator. This fact has been shown also through an empirical study.

A class of chain ratio–product type estimators with two auxiliary variables under double sampling scheme

In this paper, a chain ratio–product type estimators has been developed for estimating population mean of the study variable using two auxiliary variables under double sampling scheme, when the information on another additional auxiliary character is available along with the main auxiliary character. The optimum property of the proposed strategy has been identified in two different cases with their variances. Theoretical and empirical studies have been done to demonstrate the efficiency of the proposed estimator over other estimators, which utilized the information on two auxiliary characteristics.

Estimation of Population Mean Using Known Coefficient of Variation of the Study Character in the Presence of Non Response

Using the known coefficient of variation of the study character, generalized and regression-type estimators for the population mean using two phase sampling in the presence of non response were proposed and their properties have been studied. The conditions under which the proposed estimators are more efficient than the relevant estimators have been obtained. The empirical studies were given in the support of the problems in the case of positive and negative correlation between the study and the auxiliary characters which show the increase in the efficiency of the proposed estimators using known coefficient of variation of the study character with respect to the relevant estimators.

Ratio-Cum-Product Estimators of Population Mean Using Known Population Parameters of Auxiliary Variates

This paper suggests two ratio-cum-product estimators of finite population mean using known coefficient of variation and co-efficient of kurtosis of auxiliary characters. The bias and mean squared error of the proposed estimators with large sample approximation are derived. It has been shown that the estimators suggested by Upadhyaya and Singh (1999) are particular case of the suggested estimators. Almost ratio-cum product estimators of suggested estimators have also been obtained using Jackknife technique given by Quenouille (1956). An empirical study is also carried out to demonstrate the performance of the suggested estimators.

Proventriculus of Three Nemobiinae Crickets (Orthoptera: Grylloidea: Trigonidiidae)

The morphology of the proventriculus may supply useful taxonomic characters for some species of crickets. This study evaluated if the proventriculus can be used to distinguish three species of Nemobiinae crickets: Phoremia sp. n., Zucchiella sp. n., and Amanayara sp n. In crickets the proventriculus presents six lobes, each one bearing eight appendices along its longitudinal axis. In Phoremia sp. n., the central portion of the first appendix has a tooth like a spear, with two denticles; the central portion of the second appendix presents one plate formed by five denticles, whereas in Zucchiella sp. n., the apex of the first appendix is U-shaped with denticles absent, and the second appendices differ from those of Phoremia sp. n. by the number of denticles. In Amanayara sp. n. the central portion of the first and second appendices form a long and sharpened tooth, the denticles are lacking. In the other proventricular appendices there was variation in the number of denticles and in their shape. These results indicate that the morphology of the proventriculus can provide auxiliary characters for taxonomy of Nemobiinae, especially useful for this subfamily, since for many species the external morphology is insufficient for characterization of genera and species.

Search of Good Rotation Patterns to Improve the Precision of Estimates at Current Occasion

In rotation (successive) sampling, it is common practice to use the information collected on a previous occasion to improve the precision of the estimates at current occasion. The previous information may be in the form of an auxiliary character, the character under study itself, or both. In the present work, information on an auxiliary character, which is readily available on all the occasions, has been used along with the information on study character from the previous and current occasion. Consequently, chain type difference and regression estimators have been proposed for estimating the population mean at second (current) occasion in the two occasions rotation (successive) sampling. The proposed estimators have been compared with sample mean estimator when there is no matching and the optimum estimator, which is the combination of the means of the matched and unmatched portions of the sample at the second occasion. Optimum replacement policy is also discussed. Theoretical results have been justified through empirical interpretation.

O konwencjonalnych znakach pomocniczych w tekście polskim

The aim of this paper is to discuss the usage of four characters that can be met in Polish texts in functions different than letters and punctuation marks: apostrophe, hyphen, slash and dot (the two last characters are also used as punctuation marks ). They occur in words introduced to Grammatical Dictionary of Polish by Zygmunt Saloni, Włodzimierz Gruszczyński, Marcin Woliński, and Robert Wołosz, published in 2007. The conventional auxiliary characters have been neglected in alphabetical order and are not taken into account in searches.

On the use of transformed auxiliary variables in estimating population mean by using two auxiliary variables

This paper focuses on the use of auxiliary variables in estimating the finite population mean. We introduce a new class of estimators and compare its performance with several existing estimators such as ordinary sample mean, conventional ratio estimator and estimators by Sisodia and Dwivedi [1981. A modified ratio estimator using coefficient of variation of auxiliary variable. J. Indian Soc. Agricultural Statist. 33, 13–18], Singh and Kakran [1993. A modified ratio estimator using known coefficient of kurtosis of an auxiliary character. Unpublished manuscripts] and Upadhyaya and Singh [1999. Use of transformed auxiliary variable in estimating the finite population mean. Biometrical J. 41(5), 627–636]. The new estimator performs better than the other estimators considered here.

Estimation of finite population mean using known correlation coefficient between auxiliary characters

This paper proposes a modified ratio-cum-product estimator of finite population mean of the study variate Y using known correlation coefficient between two auxiliary characters X1 and X2. An almost unbiased ratio-cum-product estimator has also been obtained by using Jackknife technique envisaged by Quenouille (1956). The merits of the proposed estimator are examined through a numerical illustration.

Estimation of finite population mean with known coefficient of variation of an auxiliary character

This paper deals with the problem of estimating population mean Y of the study variate y using information on population mean X and coefficient of variation Cx of an auxiliary character x. We have suggested an estimator for Y and its properties are studied in the context of single sampling. It is shown that the proposed estimator is more efficient than Sisodia and Dwivedi (1981) estimator and Pandey and Dubey (1988) estimator under some realistic conditions. An empirical study is carried out to examine the merits of the constructed estimator over others.

An Approach to GIS Based Spatial Sampling Procedures for Environmental Studies in Agriculture

SYNOPTIC ABSTRACTIn this paper Geographic Information System (GIS) based spatial sampling procedures have been proposed for environmental studies in agriculture. In the proposed sampling procedures, an attempt is made to suggest a stratified sampling design in which not only the spatial nature of the environmental variables has been taken care by incorporating spatial correlation based on auxiliary character in selecting the sample but also the effect of clustering properties of environmentally polluted neighboring areal units is considered. It is proposed to stratify the study region based on neighborhood properties of the sampling units.

Location-shifts for improved estimation under Midzuno–Sen sampling scheme

Abstract Simple location-shifts for the study or auxiliary character are proposed under Midzuno–Sen sampling from a finite population. These aim at improving the efficiency of the classical Horvitz–Thompson estimator or the unbiased ratio estimator of a population total. It is demonstrated that the choice of the translation parameters is flexible. A few methods for assessing these parameters are outlined. The gain in efficiency of estimation is illustrated.

The efficiency of an alternative to ratio estimator under a super population model

Srivenkataramana and Tracy (1986) have suggested an alternative to ratio estimator. Its efficiency relative to usual unbiased estimator, ratio estimator and product estimator based on simple random sampling without replacement (SRSWOR) is studied under a super population model with uncorrelated error and a gamma distributed auxiliary character. It has been shown that the estimator forwarded by Srivenkataramana and Tracy (1986) is inferior to usual ratio estimator except when variance of study variate is constant (i.e. g=0). However, their estimator is better than the usual unbiased estimator and product estimator for a wide range of a constant involved in the estimator. Results have been supported with some numerical examples.

Estimation of population mean in successive sampling using information on auxiliary character

In this paper, the use of auxiliary information on some characters correlated with the character under study in successive sampling has been studied. A number of estimators on most recent occasion in unistage successive sampling have been developed using auxiliary information on single character besides the information on character under study at the previous occasion. The relative gains in precision of the developed estimators over the usual estimator have also been computed.

A general class of chain estimators for ratio and product of two means of a finite population

This paper proposes a class of estimators for estimating ratio and product of two means of a finite population using information on two auxiliary characters. Asymptotic expression to terms of order 0(n-1) for bias and mean square error (MSE) of the proposed class of estimators are derived. Optimum conditions are obtained under which the proposed class of estimators has the minimum MSE. An empirical study is carried out to compare the performance of various estimators of ratio with the conventional estimators.

A class of ratio, product and difference (R.P.D.) estimators in systematic sampling

A class of estimators is proposed for estimating the population parameter (mean) Y of the study character y, using information on an auxiliary character x, in systematic sampling of which the estimator is proposed by Swain [ J. Indian Statist. Ass. 2 (213), 160–164 (1964)], Sukla [ Proceedings of the All-India Seminar on Demography and Statistics, pp. 243–248. Varanasi, India (1971)] and difference estimator in systematic sampling are particular cases. The conditions in which this class of estimators performs better than other estimators are derived.

Multivariate Product Estimators

In this paper, we discuss the estimators based on geometric and harmonic mean to estimate the population mean in a finite population based on simple random sampling design when information on several auxiliary characters negatively correlated with the main variable is available. Bias and MSB of these estimators have been obtained and it is shown that these are less biased than Singh's (1967) estimate based on arithmatic mean under usually satisfied practical situations.

Some improved ratio-type estimators of finite population variance in sample surveys

This paper proposes a class of ratio-type estimators of finite population variance and variance ratio when the population variance of an auxiliary character is known. Asymptotic expressions for bias and mean square error are derived and their MSE's are compared with the MSE of usual ratio estimator t1 proposed by Isaki (1983) of the population variance of study character y. The regions are obtained under which proposed estimator is superior to t1 . When a prior knowledge of the value of coefficient of kurtosis, ;β2(y)of y is a t hand, ratio type estimator, say t2, of is suggested. It is shown, under certain conditions, that t2 is more efficient than t1. Under some further knowledge another estimator of , better than t1 and t2,is proposed. Finally, one more class of estimator is proposed and its properties are discussed. The discussions are also made in bivariate normal population

Chain ratio type estimator for ratio of two population m3ans using auxiliary characters

In this paper we have proposed chain ratio type estimators for ratio of two population means using two auxiliary characters. The expressions for bias and mean square error of these estimators have been derived. A comparison of the proposed estimator with that of double sampling estimator has been made in terms of mean square error. An emperical study has also been made.