Browsing by Author "Chakrabartty, Satyendra Nath"

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A single measure of overall export performance /
(National Council of Applied Economic Research, 2022-08-01) Chakrabartty, Satyendra Nath
Exports are a lifeline to a country’s growth, and an overall index can describe its export performance. However, there is little evidence of a single measure encompassing all the relevant aspects of exports. A composite and multi-dimensional measure can aid in assessing the relative position of a country in the world list and identifies necessary policy interventions. The article proposes an Overall Export Performance Index that satisfies the principles of index formation—monotonicity, time reversal, robustness and an unbiased approach. The proposed index avoids selecting weights and scaling variables. It facilitates the identification of crucial indicators requiring the attention of policymakers, tracking the progress of a country across time and the computing of mean and variance of the index for a group of countries at a given time. An empirical comparison of the USA and India reveals that India registered better overall export performance than the USA from 2015 to 2018. The results suggest India’s need for reforms in existing foreign trade policies.
Angular similarity in test parameters /
(SAGE Publications Ltd, 2021-01-01) Chakrabartty, Satyendra Nath
Through N-dimensional person space, the article gives measures of test parameters and item statistics, including difficulty/discriminating value of test, correlations between a pair of items, and item-total correlations with binary items using angular similarity between two vectors. Relationships between difficulty value and discriminating value of items and test were derived, including relationship between test reliability and test discriminating value. Reliability of a test as per theoretical definition in terms of length of score vectors of two parallel subtests and angle between such vectors was derived. The method was extended to find reliability of a battery of tests. Reliability and discriminating value of a Likert-type item and scale was found in terms of angular similarity without involving assumptions of continuous nature or linearity or normality for the observed variables, or the underlying variable being measured. The proposed methods also avoid test of unidimensionality or assumption of normality or bivariate normality associated with the polychoric correlations. Thus, the proposed methods are in fact nonparametric and considered as improvement over the existing ones. Reliability as a measure of association of two vectors and discrimination as a measure of distance between the vectors are likely to show a negative relationship.
Assessing a country's sector-specific logistics performance: the case of india's marine-product sector /
(Penerbit UMT, 2022-12-30) Chakrabartty, Satyendra Nath
Country-wise Logistics Performance Index (LPI) is insufficient to guide changing policies for different sectors with varied logistics requirements and perspectives. Each perspective has various measures, and hence a battery of scales is mandated to measure the performance for an individual sector like marine, agriculture, and similar. For the marine-product sector of India, scores are transformed and combined to follow normal distributions enabling parametric analysis. A method of sector-specific logistics performance index (LPI-S) is proposed addressing multi-dimensional, multi-scale response categories satisfying the desired properties of an index. An empirical illustration is given to assess LPI-S for the marine-product sector in India, combining responses of 141 Indian marine exporters in a battery with nine dimensions. The proposed method generates continuous, monotonic data, and distributions of dimension/battery scores are normal. The LPI-S scores have better arithmetic aggregation admissibility, even if lengths of dimensions are different. In addition, it identifies critical dimensions, detects changes by longitudinal data, and dimension-wise elasticity reflecting the sensitivity of the dimension from snap-shot data. Irrespective of dimensions and types of data, the proposed methodology uses the sensitivity of a dimension on LPI-S to help policy makings separately for individual categories to improve logistics efficiency. The study identified eight crucial dimensions associated with marine product logistics. The sensitivity of these dimensions in the descending order of importance were - Information system, Regulatory process, Safety & Security issues, Timeliness and Completeness efficiency, Sustainability in logistics, Operating conditions, Logistics facility pricing, Quality of Logistic services, Transportation Networks and Logistics infrastructure. Such ordering of dimensions help in deciding policy priorities.
Assessing direction of indiaâ€™s exports: a dynamic framework /
(ASEAN India Centre & ASEAN Studies Center, 2024-02-25) Chakrabartty, Satyendra Nath
Decision on trade policies with emphasis on bilateral trade relationships needs knowledge about the direction of exports of the exporting country along with associated changes like degree of specialisation, etc. The direction of export for a product or sector can be taken as a set consisting of destination countries (DCs) and corresponding export potentiality. The set reflects the direction, composition and value of trade potentials and helps to decide export-boosting measures of several sectors, focusing on a country. The paper suggests the use of ratio and geometrically aggregated revealed comparative advantage (RCA) values for individual and combined sector growth (positive or negative), respectively. This approach overcomes the static properties of RCA and shift-share analysis typically used to reveal the patterns of trade direction. The pattern is investigated by geometric aggregation of ratios of RCA at the current period over the base period for each sector. The index follows log-normal distribution and shows fluctuations of RCA for a product/sector across time. Such curves of fluctuations for different countries may facilitate meaningful inter-country comparisons. Second, this paper suggests the use of bilateral RCA to determine the direction of India’s exports for a particular sector, enabling the determination of its potential markets.
Association between multiple sclerosis and cardiovascular dysfunction /
(Crimson Publishers, 2023-04-28) Chakrabartty, Satyendra Nath
Background: Empirical studies indicate association of Multiple Sclerosis (MS) with increased risks of Cardiovascular Diseases (CVDs). However, controversial results emerged. Objectives: To measure the association between MS and CVD using pathological data and scales to assess s MS and CVD. Methods: The paper provides an assumption-free method to convert item scores to normally distributed scale scores, avoiding limitations of scales to assess MS or CVD satisfying desired properties. Binary and categorical pathological data may also be transformed to follow normal and data in ratio scale may be standardized followed by transformation and added with scale scores. Result: Association through contingency table need meaningful scale scores to obtain the cell frequencies. Proposed scores can classify the sample in relevant classes through equivalent scores and find cell frequencies. Associations by correlations are preferred over frequency based measures. However, correlations may not imply linearity. Conclusion: Normally distributed proposed scores ensure meaningful addition of item scores to get dimension/scale scores for individuals and contribute to improve scoring of instruments. Such scores facilitate better comparisons, measurement of association, statistical tests and identification of areas requiring changes in clinical practice, treatment protocols, community program management and estimating population parameters and testing of statistical hypothesis.
Constructing aggregated revealed comparative advantage index of a country /
(ASEAN-India Centre & ASEAN Studies Center, 2023-02-12) Chakrabartty, Satyendra Nath
The measures of revealed comparative advantage (RCA) with multiplicative specification and dependency on world trade of export items are incomparable across time and places. Intra-country comparisons by Balassa RCA and its variants are problematic, calling for a method of aggregating RCA of all sectors of a country reflecting the overall export potential of the country. Overall RCA of a country (RCA) is necessary to know the country’s RCA of all the export items as a function of trade flows relative to a point of reference, that is, a base period. The article proposes geometric aggregation of the ratio of RCA at the current period over the base period for each sector to get by a continuous, monotonically increasing function of time, satisfying time-reversal test, formation of chain indices and generates time-series data. Progress path of and similar path of jth sector may help policymakers to decide on appropriate action for the economy and individual sectors. Distribution of will approach lognormal. Knowledge of distributions of for different countries helps to have a better inter-country comparison. The similarity of two RCA curves may be evaluated by similarity measures. An empirical illustration of the proposed method is given.
Cosine similarity approaches to reliability of likert scale and items /
(Hyperion University, 2018-02-02) Chakrabartty, Satyendra Nath
Based on cosine similarities, the paper proposes two non-parametric methods of finding reliability of Likert items and Likert scale from single administration of the questionnaire, considering only the frequency or proportion for each cell of the Item-Response category matrix without involving any assumptions of continuous nature or linearity or normality for the observed variables or the underlying variable being measured. Each method enables to find reliability irrespective of distribution of the observed or underlying variables and avoiding test of uni-dimensionality or assumption of normality for Cronbach's alpha or bivariate normality for polychoric correlations. The proposed methods thus are considered as improvement over the existing ones. Reliability as per Bhattacharyya's measure appears to be preferred over the Angular Association method as the former expresses test reliability as a function of item reliabilities. In addition to offering the computational steps, empirical verification with real data is given to illustrate the concepts and usefulness of the proposed non-parametric reliability procedures.
Drug addiction and quality of life: methodological issues /
(URF Publishers, 2023-06-09) Chakrabartty, Satyendra Nath
Objective: Substance abuse research data containing categorical and continuous variables often violate assumptions of parametric statistical methods. Clustering of individuals, lack of repeated measurements, missing data, non-representative samples, etc. aggravates the problem. Quality of life (QoL) measures suffer from meaningful application of statistical methods. The paper describes statistical approaches which fit well with structure of drug addiction data and measures of QoL, facilitating better analysis and interpretations of results. Method: Converting ordinal item scores to normally distributed continuous scores in the range [1-100], irrespective of number of response-category in items. Such transformations fit well with structure of drug addiction data and measures of QoL and facilitate better analysis and interpretations of results. Results: Proposed method enables parametric statistical analysis leading to meaningful comparisons and inferences, finding equivalent scores, computation of responsiveness of the scale i.e., ability to assess changes across time and psychometric qualities like reliability, as per definition, Factorial validity reflecting the main factor for which the test was developed. Conclusions: Considering theoretical advantages, the proposed method generating normally distributed scores is recommended. Future studies with longitudinal data suggested finding sensitivity with emphasis on progression of disease and to different therapeutic interventions.
Estimation of true scores, true score variance, reliability and tests of parallelism /
(Journal of Modern Applied Statistical Methods, 2022-07-21) Chakrabartty, Satyendra Nath
Under classical test theory the paper presents a methodto find test reliability (𝑟𝑡𝑡)as per theoretical definition from a single administration of the test, involving dichotomization of a test in parallel halves. The method helps to find point and interval estimations of test reliability, individual true score, true score variance, error varianceand testing 𝐻𝑜:𝑟𝑡𝑡=1. Dichotomization of a test in parallel halves requires simultaneous testing of equality of mean, variance and correlation for two parallel sub-tests (𝑋𝑔and𝑋ℎ)which can be done by testing (i) equality of regression line of observed score 𝑋on𝑋𝑔and 𝑋on𝑋ℎ(ii)equality of correlations between 𝑋and 𝑋𝑔and𝑋and 𝑋ℎ, (iii) Normality of (𝑋𝑔−𝑋ℎ)or (iv) Cosine similarity (without assuming normal distribution of 𝑋𝑔and𝑋ℎ). Reporting of theoretically defined reliability along with SD of true score/error score is recommended for a test.
Measurements in mental tests through person space /
(Springer Nature, 2020-08-29) Chakrabartty, Satyendra Nath
If a test is administered to n-persons, the test score can be viewed as a point in n – dimensional person space where each person is considered in an axis and the variables are represents as points or vectors. The orthogonality of the axes is better indication since individuals are assumed to be independent. Such presentation helps to make useful inferences about the subjects and various parameters of the test, item statistics along with geometrical interpretation of such computations. For a test consisting of one-right-rest wrong type items, the paper gives theoretical formulation of mental testing through person space, primarily in terms of length of observed score vector and angle separating the vector with the vector representing the maximum possible score in the test. In addition, method is described to obtain (i) test reliability, as per the theoretical definition, via a single administration of the test, which is extended to find reliability of a battery of tests (ii) difficulty, discriminating values of items and test along with their relationships. Empirical verification of the proposed methods are undertaken.
Optimum number of response categories /
(Springer Nature, 2021-05-28) Chakrabartty, Satyendra Nath
Through linear transformations of raw item scores, the paper converts 3-ponit, 4-point, 5-point and 7-point items to continuous, monotonic, normally distributed scores ranging between 1 to 5. This provides a platform for meaningful comparisons of scales with different number of response categories with respect to parameters like reliability, validity, discriminating power, and undertakes analysis in parametric set up. The method makes no assumption of continuous nature or linearity or normality for the observed variables or the underlying variable being measured. Thus, the assumption-free simple method can have wide applicability. Use of such methods of converting scores of Likert items is recommended for clear theoretical advantages and easiness in calculations. Inverse relationship derived between new measures of test discriminating value in terms of co-efficient of variation (CV) and theoretically defined test reliability. Empirically, such inverse relationship was observed for the scales. Number of response categories did not show much influence on discriminating value, reliability and factorial validity, even for the transformed normalized scores in the range 1 to 5. Thus, the study could not find optimum number of response categories which maximize validity, reliability or discriminating value. Future studies with multi-data set for generalization of findings are suggested.
Scoring of health state utility instruments for better comparability /
(Zenodo, 2021-12-31) Chakrabartty, Satyendra Nath
Background: Health state utility (HSU) instruments differ in descriptive system, domains considered, scoring methods, analysis of ordinal data without checking limitations and assumptions of such analysis. A high score indicates higher favorable health state for SF 36, HUI 3, SF 6D, AQoL (response scores)unlike scales like EU-5D-5L, 15 D. Objectives: To provide method for converting item-response scores to continuous, monotonic, normally distributed scores in 1 to 100, avoiding limitations of existing HSU scales with different number of items and different number of levels. Materials and Method: The methodological paper involves no data from patients. Here, health state of an item score is transformed to equidistant-scores by weighted sum where weights are based on frequency of responses to each level of an item. Weights are different for different levels of different items. Standardize Y-scores to Z-scores and convert Z-scores to proposed scores ( in the range 1 to 100. Scale scores as sum of follows normal distribution. Results: P-scores facilitate inferences like estimation and testing of statistical hypothesis on equality of population parameters either for longitudinal or snap-shot data, assessment of progress/deterioration by a patient or a group of patients. Equivalent score combinations ( to integrate two HSUs were found. Conclusions: The proposed method avoids differences due to descriptive systems, scale effects, utility algorithms, etc. and contributes to improve scoring of HSU instruments avoiding limitations of ordinal scores and facilitating analysis under parametric set up for meaningful comparisons.
Scoring of health state utility instruments for better comparability /
(Zenodo, 2021-12-23) Chakrabartty, Satyendra Nath
Background: Health state utility (HSU) instruments differ in descriptive system, domains considered, scoring methods, analysis of ordinal data without checking limitations and assumptions of such analysis. A high score indicates higher favorable health state for SF 36, HUI 3, SF 6D, AQoL (response scores)unlike scales like EU-5D-5L, 15 D. Objectives: To provide method for converting item-response scores to continuous, monotonic, normally distributed scores in 1 to 100, avoiding limitations of existing HSU scales with different number of items and different number of levels. Materials and Method: The methodological paper involves no data from patients. Here, health state of an item score is transformed to equidistant-scores by weighted sum where weights are based on frequency of responses to each level of an item. Weights are different for different levels of different items. Standardize Y-scores to Z-scores and convert Z-scores to proposed scores ( in the range 1 to 100. Scale scores as sum of follows normal distribution. Results: P-scores facilitate inferences like estimation and testing of statistical hypothesis on equality of population parameters either for longitudinal or snap-shot data, assessment of progress/deterioration by a patient or a group of patients. Equivalent score combinations ( to integrate two HSUs were found. Conclusions: The proposed method avoids differences due to descriptive systems, scale effects, utility algorithms, etc. and contributes to improve scoring of HSU instruments avoiding limitations of ordinal scores and facilitating analysis under parametric set up for meaningful comparisons.
Statistics in cancer: diagnosis, disease progression, treatment efficacy, and patient survival studies /
(Springer Nature, 2022-01-01) Chakrabartty, Satyendra Nath
This article proposes a simple nonparametric measure for diagnosis of cancer and assessing cancer intensity for an individual, without resorting to group data or reduction of dimensionality or scaling or finding weights. The measure also identifies the critical areas/variables requiring attention, can be applied for all non-nominal data, can be used to find mean, variance, and confidence interval for group data, and facilitates statistical tests of hypothesis. The cancer intensity facilitates ranking/classifying a group of patients along with quantifying progress of treatment at individual and group level. Using suitably designed group data, attempt can be made to find a small interval of values of cancer intensity for each type of cancer, which may be associated with Stage IV cancer or metastatic cancer. The proposed measure of cancer intensity offers an alternative approach for estimation of survival function of cancer patients. This study leads to a number of new areas of statistical analysis in cancer treatment. An empirical study will be of vital interest based on this theoretical study.
Understanding national level logistics costs: methodological approach /
(ASEAN-India Centre & ASEAN Studies Center, 2022-07-01) Chakrabartty, Satyendra Nath
Logistics cost (LC) estimated by different methods are not comparable since cost components differ across countries and are not properly standardised, non-availability of comprehensive reliable data on LC and presence of number of qualitative components. No method of measuring LC has considered probability distributions of the components/dimensions. After review of methods to estimate LC, the article proposes to transfer the j-th component score emerging from questionnaire-based approach to a proposed score (Pi) so that and follows normal distribution. Logistics cost index (LCI) of i-th country is taken as multiplicative aggregation of ratios of at the current period and base period of all components. The index avoids perfect substitutability of arithmetic aggregation, and it satisfies the desired properties of an index including time-reversal test and formation of chain-indices, and enables meaningful comparisons across time and space, better ranking and classifying the countries, identification of critical dimensions/components requiring policy changes, drawing path of decline or increase of LCI over time for a country, computing mean LCI for a group of countries and LCI at Global level, and undertaking statistical analysis under parametric set up. Future investigations suggested reflecting properties of the proposed LCI along with empirical relationships of sector-wise LCI and economic development. JEL Codes: D57, E23, P44