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Showing papers on "Sampling (statistics) published in 1974"


Journal ArticleDOI
TL;DR: Seven major types of sampling for observational studies of social behavior have been found in the literature and the major strengths and weaknesses of each method are pointed out.
Abstract: Seven major types of sampling for observational studies of social behavior have been found in the literature. These methods differ considerably in their suitability for providing unbiased data of various kinds. Below is a summary of the major recommended uses of each technique: In this paper, I have tried to point out the major strengths and weaknesses of each sampling method. Some methods are intrinsically biased with respect to many variables, others to fewer. In choosing a sampling method the main question is whether the procedure results in a biased sample of the variables under study. A method can produce a biased sample directly, as a result of intrinsic bias with respect to a study variable, or secondarily due to some degree of dependence (correlation) between the study variable and a directly-biased variable. In order to choose a sampling technique, the observer needs to consider carefully the characteristics of behavior and social interactions that are relevant to the study population and the research questions at hand. In most studies one will not have adequate empirical knowledge of the dependencies between relevant variables. Under the circumstances, the observer should avoid intrinsic biases to whatever extent possible, in particular those that direcly affect the variables under study. Finally, it will often be possible to use more than one sampling method in a study. Such samples can be taken successively or, under favorable conditions, even concurrently. For example, we have found it possible to take Instantaneous Samples of the identities and distances of nearest neighbors of a focal individual at five or ten minute intervals during Focal-Animal (behavior) Samples on that individual. Often during Focal-Animal Sampling one can also record All Occurrences of Some Behaviors, for the whole social group, for categories of conspicuous behavior, such as predation, intergroup contact, drinking, and so on. The extent to which concurrent multiple sampling is feasible will depend very much on the behavior categories and rate of occurrence, the observational conditions, etc. Where feasible, such multiple sampling can greatly aid in the efficient use of research time.

12,470 citations


Journal ArticleDOI
TL;DR: This paper examines the effect of visibility bias, discusses the means by which the bias arises, and suggests methods by which it might be eliminated from aerial survey estimates of density and population size.
Abstract: Aerial censuses of large mammals are inaccurate because the observer misses a significant number of animals on the transect. The accuracy deteriorates progressively with increasing width of transect, cruising speed, and altitude. Methods of eliminating bias by refining techniques are discussed and rejected; there seems to be no technical solution. An alternative strategy is to measure the bias and correct the estimates accordingly. A method is suggested for estimating bias during an aerial census, the subsequent analysis returning an unbiased estimate of density. No direct measure of true density is needed and little extra effort is involved over that required for a standard aerial survey. J. WILDL. MANAGE. 38(4):927-933 This paper examines the effect of visibility bias, discusses the means by which the bias arises, and suggests methods by which it might be eliminated from aerial survey estimates of density and population size. Aerial survey is, at best, a rough method of estimating the size of a population. Most efforts at refinement have been aimed at raising the precision of the estimate by combining impeccable survey design, high sampling intensity, intricate stratification, and powerful methods of analysis. This trend can be traced back to Siniff and Skoog's (1964) superb paper on an aerial census of caribou (Rangifer tarandus). Their use of stratified random sampling, with sampling effort allocated proportional to density, contrasted markedly with the crudity of previously reported surveys. Subsequently, Jolly's (1969a) paper on designs and analyses appropriate to aerial survey has encouraged a rigorous and disciplined application of the method. Recent papers following this lead have tended to treat the difficulties of estimating population size from the air largely as constituting a sampling problem, a survey being rated successful or otherwise according to the size of the estimate's standard error. Tacitly, the standard error was treated as a measure of the estimate's accuracy rather than of its repeatability. Underlying the preoccupation with precision there often lurked an implicit assumption that the estimate is free of bias, that the observers counted all animals on each sampled

384 citations


Journal ArticleDOI
TL;DR: In this paper, the authors give simple formulas relating the aspiration coefficients to a number of parameters determining the aspiration process, and the results obtained with the help of the formulas are compared with reliable experimental data.

216 citations


Book
01 Jan 1974

168 citations


Journal ArticleDOI
TL;DR: In this paper, a procedure for the synthesis of processes exhibiting temporal and spatial variability is presented, which involves the addition of harmonics of random frequencies that are sampled from the spectral density function or the radial spectral density functions.
Abstract: A procedure for the synthesis of processes exhibiting temporal and spatial variability is presented The method involves the addition of harmonics of random frequencies that are sampled from the spectral density function or the radial spectral density function The process obtained is asymptotically Gaussian and ergodic An estimate of the error in time or space averages due to the nonergodicity of the process as a function of the number of harmonics is also included

151 citations


01 Sep 1974
TL;DR: In this article, the authors analyzed the relationship between employees' task goals and supervisory performance as moderated by n Achievement among a sample of first-level supervisors working under a formalized goal-setting program.
Abstract: Abstract This investigation analyzes the relationship between employees' task goals and supervisory performance as moderated by n Achievement among a sample of first-level supervisors working under a formalized goal-setting program. Before need strength levels were taken into account, little consistent relationship was found between the five task-goal attributes and performance. After dividing the subjects into high and low n Ach groups, however, it was found that performance was significantly related to increases in feedback and in goal specificity for high n Ach subjects, and to participation in goal-setting for low n Ach subjects. Goal difficulty and peer competition were found to be unrelated to performance for both groups. These results are then compared to other studies on the topic and it is concluded that individual difference factors, like n Achievement, must be taken into account in any comprehensive theory of goal-setting in organizations.

147 citations


Journal ArticleDOI
TL;DR: In this article, Ewens has considered the problem of inferring whether the genotypic frequencies observed in a small sample are consistent with a particular population model, in which all types are selectively neutral.
Abstract: In a paper of the same title, Ewens has considered the problem of inferring whether the genotypic frequencies observed in a small sample are consistent with a particular population model, in which all types are selectively neutral. The present paper gives the general theory of such sampling schemes, when the sampling is from either a deterministic, or a stochastically varying, population. The theory is illustrated on a population model which was introduced by Karlin and McGregor. Various results are proved for both the population, and its sample. It is shown that Ewens' sampling theory applies to this population model, and conjectures as to why different population models may have the same sampling theory are made.

139 citations



Journal ArticleDOI
TL;DR: Functional relationships are presented to determine the sampling, subsampling, and analytical variance for any size sample, subsample, and number of analyses.
Abstract: Using 12 lb samples, 280 g subsamples, the Waltking method of analysis, and densitometric procedures, the sampling, subsampling, and analytical variances associated with aflatoxin test procedures were estimated. Regression analysis indicated that each of the above variance components is a function of the concentration of aflatoxin in the population being tested. Results, for the test procedures given above, showed that sampling constitutes the greatest single source of error, followed by subsampling and analysis. Functional relationships are presented to determine the sampling, subsampling, and analytical variance for any size sample, subsample, and number of analyses.

96 citations


Journal ArticleDOI
01 Feb 1974-Talanta
TL;DR: Methods are now being devised for the design of sampling schemes and for data evaluation to increase the certainty with which large, inhomogeneous, and segregated masses of material (mountains) may be analysed for interesting constituents.

88 citations


Journal ArticleDOI
TL;DR: The primary productivity of the benthic microflora was measured using in situ techniques and ranged from below 0.5 mg C m−2 h−1 in winter when the sampling area was covered with ice to nearly 57.0 mg C m-2 h-1 in August.
Abstract: The primary productivity of the benthic microflora was measured using in situ techniques. Primary productivity ranged from below 0.5 mg C m−2 h−1 in winter when the sampling area was covered with i...

Journal ArticleDOI
TL;DR: The study was conducted in the St. Lawrence estuary during 1969 and 1970 and revealed that over 95% of the available food of the common eider consisted of Littorina spp.
Abstract: The study was conducted in the St. Lawrence estuary during 1969 and 1970. The food abundance in the intertidal zone was measured in four Sampling stations located on the south shore of the river; t...


Journal ArticleDOI
TL;DR: Stratified sampling techniques are found to exhibit greater overall comparative accuracy then either random or systematic sampling, though their general behavioural properties mirror those of the parent strategy in other respects.
Abstract: The properties offour sampling models, random and its derivative stratified random sampling, systematic and its derivative stratified systematic unaligned sampling, are examined empirically with special reference to the context of vegetation survey. Some interesting behaviour patterns emerge in relation to (i) relative accuracy at high and low sample intensity, (ii) variability of estimation, (iii) performance with units of different shape and fragmentation, and (iv) stabilization across sample intensity. Stratified sampling techniques are found to exhibit greater overall comparative accuracy then either random or systematic sampling, though their general behavioural properties mirror those of the parent strategy in other respects. Finally, the different spatial properties of the models are briefly discussed.

Journal ArticleDOI
TL;DR: Soil sampling experiments were conducted on 0.01 hectare plots of Fox loamy sand in areas of low, medium, or high population densities of Pratylenchus penetrans (Cobb).
Abstract: Soil sampling experiments were conducted on 0.01 hectare (ha) plots of Fox loamy sand in areas of low, medium, or high population densities of Pratylenchus penetrans (Cobb). Nematode count data from 1, 20, and 40 core samples were statistically analysed to find normalizing transformations and to compare the efficiency of different sampling schemes. Although negative binomial distributions fitted the observed frequency distributions, normalizing transformations of the form log (x + c), that stabilized variance for all population densities, were obtained empirically. It was estimated that at least seven hours of field sampling and laboratory analysis are required to obtain an estimate of mean population density of a plot within 20 % of the true mean with 95 % confidence. An estimate of nematode population density in a 0.01 ha plot based on a subsample from one 20 or 40 core sample is shown to have very low precision.

Book ChapterDOI
TL;DR: In this paper, it is shown that the expected number of observations on the superior treatment must be at least one-half that required by pairwise sampling, and a class of sampling rules is given which for some parameter values and significance levels almost attains this theoretical bound.
Abstract: For testing which of two normally distributed treatments with a common variance is “superior” (has a larger mean response), we give a class of sequential probability ratio tests whose error probability functions are essentially independent of the sampling rule used. It is shown that the expected number of observations on the “inferior” treatment must be at least one-half that required by pairwise sampling, and a class of sampling rules is given which for some parameter values and significance levels almost attains this theoretical bound.




Patent
25 Nov 1974
TL;DR: In this article, a sampling type of metal detector is described in which an oscillator transmits an oscillators signal current through the transmit coil of the detector to produce an electromagnetic field in the region of a search head.
Abstract: A sampling type of metal detector is described in which an oscillator transmits an oscillator signal current through the transmit coil of the detector to produce an electromagnetic field in the region of a search head. A received signal is induced in the receive coil of the detector when a metal object is present within that portion of the electromagnetic field which is external to the search head. A sampling pulse generator produces sampling pulses, at a time related to the output signal of the oscillator, which are transmitted to a sampling circuit for sampling the received signal. In the preferred embodiment, the received signal is sampled at a time controlled by a phase shift adjustment means to produce an output sample voltage such that any indication due to mineral soils or other background conditions is excluded from the sample.

Journal ArticleDOI
TL;DR: In this article, sampling and subsampling diagrams provide a means of visualizing and controlling sampling error during analysis of mixtures, especially those in which a minor constituent contributes heavily to assay values.



Journal ArticleDOI
TL;DR: A method for sampling quantitatively bacteria present in the subsurface pilo-sebaceous units of human skin is described and counts of up to 106 organisms/cm2 obtained.
Abstract: Summary. A method for sampling quantitatively bacteria present in the subsurface pilo-sebaceous units of human skin is described. Less than 0.5% of a marker surface organism was isolated and counts of up to 106 organisms/cm2 obtained.

Journal ArticleDOI
TL;DR: In this article, the authors apply the jackknife method to stratified samples from a multivariate population of finite size, where the data omitted are those for a group of sampling units that cut across all strata, thereby compacting the region where approximate relationships are assumed to hold.
Abstract: SUMMARY The jackknife method of investigating and reducing the bias in nonlinear estimates of parameters is applied to stratified samples from a multivariate population of finite size. Attention is focused on estimators that can be expressed as functions of sample means. As in other applications of the jackknife method, an approximate relationship between the bias in an estimator and the sample size is exploited to reduce this bias by employing a linear combination of an estimate computed from all the data and several estimates each computed after omitting part of the data. Unlike some other applications to stratified sampling, however, where the data omitted are those for a group of sampling units that cut across all strata, the present application involves omitting just one sampling unit at a time, thereby compacting the region where approximate relationships are assumed to hold, and increasing the stability of the variance estimates. The relationships are derived by an analytic approach. Results are carried out far enough for use in second-order jackknife estimates of parameters and variances so as to eliminate bias to third-order moments of the variables observed. When there is just one stratum, the first-order estimators defined by equations (4.3) and (6-1), which are unbiased to second-order moments, are asymptotically the same -as those proposed by Tukey (1958).

Journal ArticleDOI
TL;DR: A unified analytic approach is presented for the design of adaptive sampling control law in sampled-data systems by introducing an objective function which measures the performance of the sampler over each sampling interval, and then minimize it to obtain the sampling controllaw.
Abstract: A unified analytic approach is presented for the design of adaptive sampling control law in sampled-data systems. This is accomplished by introducing an objective function which measures the performance of the sampler over each sampling interval, and then minimize it to obtain the sampling control law. A total of six different control laws, which are functions of the sampled function, are derived from the generalized objective function by selecting different weighting coefficients. More than half of these control laws are identical to existing results. Similar control laws as functions of the system output can be derived as well. Also included are some experimental results on the performances of four representative control laws in a second-order system subject to step disturbance.

Journal ArticleDOI
TL;DR: Relative size estimates of populations of selected insect species on ‘Bragg’ soybeans were determined from four 15-in.
Abstract: Relative size estimates of populations of selected insect species on ‘Bragg‘ soybeans were determined from four 15-in. sweepnet and one groundcloth-shake sampling techniques. Comparing relative estimates to absolute populations, the groundcloth-shake sampling method was the most efficient method for sampling lepidopterous larvae. This method has a low relative variation and a high fidelity to population changes but was time consuming. Sweeping upwards against the foliage of one row was the most efficient method for sampling adult Cerotoma trifurcata (Forster) and adults and nymphs of Spissitilus festinus (Say).


Journal ArticleDOI
TL;DR: In this article, some of the possible orthogonal sampling techniques for determining instantaneous values of current and voltage to facilitate digital protection of transmission lines are examined by comparison of their frequency spectra.
Abstract: This paper examines some of the possible orthogonal sampling techniques for determining instantaneous values of current and voltage to facilitate digital protection of transmission lines. The relative merits of each technique are examined by comparison of their frequency spectra. Tests to verify the results of the analytical analysis are described.

Journal ArticleDOI
TL;DR: In this article, two sampling techniques are used: (a) the collection of whole air samples or (b) the selective collection of one or more trace gases on a suitable trapping device.
Abstract: The measurement of stable atmospheric trace constituents is often separated into two steps: (a) the collection of a representative sample and (b) the analysis of the trace constituents in the laboratory. The main advantage of this approach is that the most sensitive detection methods can be used. The main disadvantage is that only a relatively limited number of data points can be taken along one sampling profile.Basically two sampling techniques are used: (a) the collection of whole air samples or (b) the selective collection of one or more trace gases on a suitable trapping device. Whole air samples are taken either in the form of grab samples or by compression of air into pressure tanks or by condensing air in cryogenically cooled vessels. Stratospheric trace gases which have been measured by these methods include: CO2, CH4, CO, H2O, H2, N2O, and the noble gases. Selective sampling is accomplished by passing air through molecular sieve beds, impregnated filters, or liquid nitrogen cooled traps. Trace ga...