COMPARISON OF RATING SCALES: SENSITIVITY, REPLICATES AND RELATIVE MEASUREMENT

The relative sensitivities of four scaling methods were assessed in central location tests with untrained judges. The scales included category scales, line scales, magnitude estimation, and a hybrid of the line and category scales. Approximate parity was observed among category scales, line scales and the hybrid scale in their ability to differentiate small physical differences. Magnitude estimation was used as efficiently as the other methods by a college population, but less efficiently by a heterogeneous sample of consumers. Judges used the scales with greater accuracy as they became familiar with the range of products to be judged. In spite of relatively small physical differences, subjects used wide ranges of the scales, supporting the view that rating scales are relative, not absolute, measuring instruments.     

A COMPARISON OF CATEGORY AND LINE SCALES UNDER VARIOUS EXPERIMENTAL PROTOCOLS

Judges were required to rate the total intensity of NaCl solutions and the sweetness of orange flavored beverages using a variety of unstructured category and line scales. Discrimination errors were noted for each type of scale. No strong differences were observed in discrimination between category and line scales although a 20-point category scale incurred fewer discrimination errors than 9-point category and line scales. Allowing judges to retaste stimuli and review and modify their scores reduced discrimination errors.     

LOGARITHMIC TRANSFORMATION OF MAGNITUDE ESTIMATION DATA AND COMPARISONS OF SCALING METHODS

Recent studies comparing magnitude estimation to other scaling methods have been criticized for failure to submit the data to logarithmic transformation before statistical analysis, a procedure which can improve the ability of magnitude estimation scaling to differentiate among products. Data from one of these studies was available for re-analysis, which was conducted both with and without logarithmic transformation of magnitude estimation, category scales and line scales. The ability of magnitude estimation to differentiate among products was improved by log transformation, while the other methods were not. Improvements were associated in pan with reductions in positive skew and improved approximation of the normal distribution. In spite of this improvement, magnitude estimation remained slightly inferior to the other methods especially in the hands of an untrained consumer sample.     

INDUCTION OF SCALING ERRORS

Judges were required to rate the total intensity of NaCl solutions using a variety of unstructured category and line scales under a 'rank-rating' protocol and a traditional protocol that did not allow retasting or the reviewing of scores. The various scales and protocols induced two types of scaling errors. The first type was named a different-stimulus error. This involved a judge rating a stronger stimulus as equal to or less than a weaker stimulus. The second type was named a same-stimulus error. This involved a judge giving different ratings to two stimuli of equal concentration. For all scales, judges made a higher proportion of same-stimulus errors than different-stimulus errors. 'Rank-rating' only reduced the proportion of different-stimulus errors. It was hypothesized that a category scale with fewer categories would induce a higher level of different-stimulus errors but lower level of same-stimulus errors. These trends were noted but not always significantly. For line scales, the equivalent hypotheses regarding line length were either weak or not supported. It would appear that increasing the length of a line scale is not always equivalent to increasing the number of categories in a category scale.     

A NEW APPROACH TO CATEGORY SCALES OF INTENSITY II: USE OF d'VALUES

Using a Rank-Rating method, d'values were obtained for stimuli from a model system using 15-point, 9-point, 7-point and 5-point category scales. For an apple/grape juice system, d'values were compared for 9-point and 7-point scales. There was general agreement on d'values among the scales, except where stimuli had their scores 'bunched'into one category: this tended to occur for the strongest and weakest stimuli for Rank-Rating and for the scales with fewer points. Bunching altered distribution variances and distorted the calculated d'values. Further study gave d'values for the discrimination of confusable stimuli, using paired-comparison and rating data, thus providing numerical measures of their relative sensitivity.     

THURSTONIAN MODELS AND VARIANCE II: EXPERIMENTAL CONFIRMATION OF THE EFFECTS OF VARIANCE ON THURSTONIAN MODELS OF SCALING

Subjects rated taste intensities using category scales under a variety of experimental protocols, which induced differences in computed values of d′. These were explained in a Thurstonian/signal detection context, by variation in the effects of adaptation changing perceived intensities (perceptual variance), by the effects of forgetting (memory variance) and by differences in the idiosyncratic ways that subjects use category‐rating scales (boundary variance).     

Relationships among biological elements (macrophytes, macroinvertebrates and ichthyofauna) for different core river types across Europe at two different spatial scales

The objective of this study was to evaluate differences in correlations among Biological Elements and environmental parameters for different river types, analysed at two different spatial scales. A total of 82 sites, with at least good ecological status, were sampled across Europe, representing three core river types: Mountain rivers (26 sites); Lowland rivers (29 sites) and Mediterranean rivers (17 sites). At each site samples of macrophytes, macroinvertebrates and fishes were taken during spring, following the methodological procedures established by the European STAR project. Environmental parameters were also recorded, based on a site protocol developed by the European projects AQEM and STAR. Environmental parameters were divided into three categories: aquatic habitats (mesohabitat scale), global features (reach scale) and obligatory typology parameters of Water Framework Directive (WFD) (geographical scale). Data were analysed to evaluate at the two scales, first, relationships among biological elements, and second, relationships between biological elements and environmental parameters. Within each river type, correlation matrices (Bray–Curtis distance) were calculated separately for each biological element and for each category of environmental parameters. All biological elements were correlated (p<0.01) to the larger spatial scale: macrophytes and macroinvertebrates are more correlated in lowland and mountain rivers, while in Mediterranean rivers, fish and macrophytes presented higher correlations. These links tend to be consistent for different spatial scales, except if they are weak on a larger regional scale, obligatory parameters of WFD were, in most cases, significantly correlated with the three biological communities (p<0.05). Results at different spatial scales supported the hierarchical theory of river formation. Reach and mesohabitat environmental parameters tend to explain aquatic communities at a lower spatial scale, while geographical parameters tend to explain the communities at a major spatial scale.     

HEDONIC SCALES ARE A BETTER PREDICTOR THAN JUST-ABOUT-RIGHT SCALES OF OPTIMAL SWEETNESS IN LEMONADE1

A comparison of hedonic scales and just-about-right (JAR) scales is needed because data in previous studies using JAR scales suggest that predicted optimum levels of ingredients often are not the same as the levels in products that currently are sold successfully. Thus, in this research, consumers tested lemonade varying in sugar concentration from 6% to 14%, using (1) a JAR scale formed by boxes or a line and (2) a hedonic box-type scale. Predicted “optimum” levels of sweetness for the lemonade and differences in liking for the formulations were determined. The JAR line and box scales gave similar predicted optimal results (9.2% and 9.4% sucrose, respectively), which were significantly lower than the hedonic scale results (10.3% sucrose). In a preference test, consumers significantly preferred the 10.3% sugar lemonade over the 9.3% concentration, indicating that, based on paired preference testing, the hedonic scale resulted in better prediction of optimal sweetness than the JAR scale.     

Effect of ploidy on scale-cover pattern in linear ornamental (koi) common carp Cyprinus carpio

The effect of ploidy on scale-cover pattern in linear ornamental (koi) common carp Cyprinus carpio was investigated. To obtain diploid and triploid linear fish, eggs taken from a leather C. carpio female (genotype ssNn) and sperm taken from a scaled C. carpio male (genotype SSnn) were used for the production of control (no shock) and heat-shocked progeny. In heat-shocked progeny, the 2 min heat shock (40° C) was applied 6 min after insemination. Diploid linear fish (genotype SsNn) demonstrated a scale-cover pattern typical for this category with one even row of scales along lateral line and few scales located near operculum and at bases of fins. The majority (97%) of triploid linear fish (genotype SssNnn) exhibited non-typical scale patterns which were characterized by the appearance of additional scales on the body. The extent of additional scales in triploid linear fish was variable; some fish had large scales, which covered almost the entire body. Apparently, the observed difference in scale-cover pattern between triploid and diploid linear fish was caused by different phenotypic expression of gene N/n. Due to incomplete dominance of allele N, triploids Nnn demonstrate less profound reduction of scale cover compared with diploids Nn.     

Lateral line deformities in wild and farmed sea bass (Dicentrarchus labrax,L.) and sea bream (Sparus aurata,L.)

The lateral line of aquaculture fishes has rarely been studied although it is a very important anatomical organ that could serve as an inexpensive and easy tool to distinguish farmed from wild individuals. In the present study, lateral line deformities were examined in both wild and farmed sea bass (Dicentrarchus labrax) and sea bream (Sparus aurata) specimens to try to detail all possible differences between them. In order to do so, the morphology of the trunk lateral line in wild and farmed adults was examined whereby two major deformities were observed in both species: the ‘scale pocket’ deformity (14–40% incidence in all groups) where the specialized scales are missing but the canal underneath is present and the scale print is obvious, and the ‘somatic scales’ deformity (14–56% incidence in farmed individuals only) where the missing lateral line is covered with normal somatic scales. Histological examination confirmed the macroscopic observations in that the lateral line mechanism was present – although damaged – beneath the scale pocket deformity and completely absent beneath the somatic scales deformity. It is argued that the scale pocket deformity is a result of an accident during the life of the fish whereas the somatic scales deformity is an actual deformity in development.     

SELECTING PRODUCTS FOR CATEGORY APPRAISAL STUDIES — FEWER PRODUCTS DO ALMOST AS WELL AS MANY PRODUCTS

This paper analyzes the results of different strategies for selecting test products in category appraisals. The three strategies are random selection of products from the marketplace, selection on the basis of consumer sensory data, and selection on the basis of expert panel data. All three methods generate stable results for category appraisals. The stability of the results (e.g., in terms of 'drivers of liking') increases very quickly and then levels off, suggesting that the researcher does not have to work with a particularly large number of products in a category appraisal to understand the sensory-liking dynamics.
It appears in our case, that 18 products were an appropriate number to strongly reflect results for 50 products. Researchers need to be sensitive to the variation in each category. Some categories may require more or less than this number of products to cover all the sensory ranges within the specific category.     

DEVELOPMENT AND APPLICATION OF TEXTURE REFERENCE SCALES

Standard texture rating scales of hardness, adhesiveness, fracturability, cohesiveness, and denseness were modified during the training of a Texture Profile panel. New reference materials were selected for each scale to better illustrate the texture characteristics and intensities and to account for previously recommended food products no longer available. In addition, new reference scales for wetness, adhesiveness to lips, roughness, self-adhesiveness, springiness, cohesiveness of mass, moisture absorption, adhesiveness to teeth, and manual adhesiveness were developed. The application of new texture reference scales reduced the variability among panelists and provided consistent judgments in texture evaluations. Expanded and improved definitions and evaluation procedures for texture attributes are presented. Also, special considerations for the use of reference scales in texture evaluations are discussed.     

Ontogeny and phylogeny of the trunk lateral line system in cichlid fishes

An examination of the ontogeny of the lateral line trunk canal and the diversity of adult trunk canal patterns among cichlids indicates that bidirectional canal formation is a general ontogenetic pattern in the Cichlidae with the exception of Cichla and those few species with a complete trunk canal pattern. In addition to the tubed scales which make up the trunk canal, some lateral line scales have pits containing superficial neuromasts. These are recognized as components of the lateral line system of the trunk in adult cichlids for the first time. Eight trunk canal patterns that are variations on a simple disjunct pattern are defined among the 17 cichlid genera examined. Using bidirectional canal formation as a developmental model, these patterns can be placed along an ontogenetic spectrum. This suggests that heterochrony (alterations in the timing of development) is an important mechanism of evolutionary change in the lateral line system of the trunk in cichlid fishes.     

Meristic variation among world hatchery stocks of rainbow trout,Salmo gairdneri Richardson

Synopsis Sixteen meristic characters were examined among 10 stocks of rainbow trout to establish their inter- and intrastock variability and relative discriminating power. The number of vertebrae, dorsal fin rays, scales above and below and lateral line, oblique scale rows and pectoral fin rays were found to be the most useful meristic characters in identifying stocks. Examination of the extent of meristic divergence among 10 hatchery or naturalized stocks from various regions of the world, using analysis of variance, the generalized distance function and per cent overlap, revealed that each stock exhibited highly significant differences in at least one meristic character, thereby demonstrating a high degree of intraspecific variability in meristic expression.In multivariate terms, stocks from Idaho and Alaska were almost totally divergent from all other stocks examined. Multivariate analysis of meristic features proves to be a useful method for identifying the extent of phenotypic variability among and within divergent stocks of rainbow trout. The observed meristic variability in test stocks of hatchery fish is seemingly genetically set within the limits previously described for native populations of rainbow trout.     

Quantitative Trait Loci Analyses for Meristic Traits in Oncorhynchus mykiss

Meristic trait variation among species and populations has long been used as the basis for identification and classification of fishes. Within Oncorhynchus mykiss, there is considerable variation in meristic characters such as numbers of vertebrae, lateral line scales, fin rays, gill rakers, and pyloric caeca. In our laboratory the Oregon State University (OSU) rainbow trout and the Clearwater River (CW) steelhead trout clonal lines, produced by androgenesis, exhibit significant differences in values for meristic traits, making quantitative trait locus (QTL) analysis of these meristic characters possible. Our objective was to determine the number, location, and effects of QTL associated with meristic characters in order to test two hypotheses: (1) that QTL for different meristic traits co-localize to the same linkage group and (2) that meristic trait QTL co-localize to the same linkage group as a previously identified development rate QTL. Doubled haploid individuals, produced by androgenesis from sperm from an F₁ hybrid between the OSU and CW lines, were used to evaluate the joint segregation of each meristic phenotype and Amplified Fragment Length Polymorphic marker genotypes. Composite interval mapping revealed QTL for six of the seven traits analyzed. One QTL each for scales above the lateral line and for gill rakers co-localized to the same position. Only one QTL for scales above the lateral line co-localized to the same region as that for the development rate QTL, but a greater map resolution is necessary to determine if these loci are truly the same. We failed to detect pleiotropy for most meristic trait QTL. Our results suggest that different major loci are associated with variation in each meristic character and that the expression of these loci may be influenced by maternal and external environmental factors.     

Scales of spatial patterns of distribution of intertidal invertebrates

Few comparative studies of spatial patterns at different scales have examined several species in the same habitat or the same species over a range of habitats. Therefore, variability in patterns among species or among habitats has seldom been documented. This study quantifies spatial patterns of a suite of intertidal snails and a species of barnacle using a range of statistical techniques. Variability in densities was quantified from the scale of adjacent quadrats (over a distance of centimeters) to tens of kilometers. Significant differences in abundances occurred primarily at two spatial scales. Small-scale differences were found at the scales of centimeters or 1–2 m and, for many species on many shores, these accounted for most of the variability in abundances from place to place. These are likely to be determined by behavioural responses to small-scale patches of microhabitat. Large-scale differences in abundance were also found in most species at the scale of hundreds of meters alongshore. These are likely to be due to variation in recruitment (and/or mortality) because of limited dispersal by adults of these species. There was little or no additional variation among shores, separated by tens of kilometers, than was shown among patches of shore separated by hundreds of meters. Identification of the scale(s) at which significant differences in abundance are found focus attention on the processes (and the scales at which these processes operate) that influence patterns of distribution and abundance. Some of the advantages and disadvantages of various procedures are discussed.     

Species turnover in Amazonian frogs: low predictability and large differences among forests

The factors explaining species turnover at different spatial scales have been intensively studied, but most work in Amazonia has mainly focused on plants. For animals, it is not as obvious which environmental variables most affect differences in species composition among sites. We sought to identify what causes anuran turnover in Amazonian terra firme forests, and how the effectiveness of these factors varies among regions and across spatial scales. We sampled frogs in 56 plots along ponds and streams distributed over three terra firme forest areas in Eastern Amazonia. Using multiple regressions on distance matrices, we partitioned the variation in species turnover into components explained by variation in environmental and spatial distances. This was done in parallel for each area separately, and for all areas together, to assess the consistency of results between scales and across areas at the same scale. Each community seemed to respond to a set of factors specific to that area, and the identity of the variables that emerged as significant differed among areas and scales. Both geographical distances and environmental differences had larger explanatory power at the regional scale than at the local scale. The large differences among results from different areas caution against making broad generalizations about species turnover patterns from a single community, as real differences may exist among areas.