• Title/Summary/Keyword: Difference-in-Differences Method

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Proposal of Research Methodology Using The Measurement of Perception Difference

  • YANG, Hoechang
    • Journal of Wellbeing Management and Applied Psychology
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    • v.2 no.2
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    • pp.39-45
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    • 2019
  • The purpose of this study is to solve the problem of revision or abbreviation of questionnaires based on the previous studies suggested by many existing empirical studies. In addition, this study aims to provide the theoretical basis of the research method which has been variously approached since it presents the methodology that can directly measure the research object. For this purpose, this study proposed a more elaborate analysis method using the differences in perception of individuals who are interested in cognitive research. Specifically, the perception gap(D) can be used as an independent variable, a dependent variable, and a moderating variable. And this study suggested an effective research approach using the measurement of perception difference. The difference of perception suggested that it can be used as a measure to overcome the limitations of existing researches used it as independent variables or mediating variables that measure only one factor of expectation and performance or importance and satisfaction. In addition, it is highly likely that various analyzes on the perception differences, which are the result of measuring target factors for the same person, will be quite effective in the situation where follow-up of respondents is difficult. This study is expected to overcome various limitations reported by empirical studies such as scale utilization problem and follow-up survey difficulty. In future research, it was expected that the limitation of the factor derivation process in the research approach could be complemented by web crawling and text mining of big data analysis.

The Effect of Group Mean Differences upon Factor Analysis (상관행렬의 구조분석에서 집단평균차이의 효과: 요인분석기법을 중심으로)

  • 김청택;이소영
    • Proceedings of the Korean Association for Survey Research Conference
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    • 2001.04a
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    • pp.109.2-130
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    • 2001
  • The purpose of this study is (1) to demonstrate that ignoring group differences may mislead to incorrect conclusion when analyzing correlation data (e.g., factor analysis), (2) to highlight the importance of the data analytic method considering group differences, and (3) to provide ways of incorporating group differences in data analysis. In study, 1, ignoring group difference in factor analysis may mislead to incorrect factor structure. To remedy this, z-transform method and group analysis tool in covariance structure models were suggested. In study 2, the group differences effect was illustrated by using real data (IQ test data).

The Effect of Group Mean Differences upon Factor Analysis (상관행렬의 구조분석에서 집단평균차이의 효과: 요인분석기법을 중심으로)

  • 김청택;이소영
    • Survey Research
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    • v.2 no.2
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    • pp.109-130
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    • 2001
  • The purpose of this study is (1) to demonstrate that ignoring group differences may mislead to incorrect conclusion when analyzing correlation data (e.g.. factor analysis). (2) to highlight the importance of the data analytic method considering group differences. and (3) to provide ways of incorporating group differences in data analysis. In study 1. ignoring group difference in factor analysis may mislead to incorrect factor structure. To remedy this. z-transform method and group analysis tool in covariance structure models were suggested. In study 2. the group differences effect was illustrated by using real data (IQ test data).

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New approach method of finite difference formulas for control algorithm (제어 알고리즘 구현을 위한 새로운 미분값 유도 방법)

  • Kim, Tae-Yeop
    • Journal of IKEEE
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    • v.23 no.3
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    • pp.817-825
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    • 2019
  • Difference equation is useful for control algorithm in the microprocessor. To approximate a derivative values from sampled data, it is used the methods of forward, backward and central differences. The key of computing discrete derivative values is the finite difference coefficient. The focus of this paper is a new approach method of finite difference formula. And we apply the proposed method to the recursive least squares(RLS) algorithm.

The Medial Antebrachial Cutaneous Nerve : Orthodromic and Antidromic Conduction Studies (아래팔 내측분지신경의 자극하는 방법에 따른 신경전도검사의 비교)

  • Kwak, Jae Hyuk;Lee, Dong Kuck
    • Annals of Clinical Neurophysiology
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    • v.7 no.2
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    • pp.83-87
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    • 2005
  • Background: The study of the medial antebrachial cutaneous nerve (MABCN) is an underused electrodiagnostic tool. But its use is often crucial for assessing mild lower brachial plexus or MABCN lesions, and sometimes for differentiating an ulnar mononeuropathy from a lower brachial plexopathy. This study was designed to know the difference of amplitude and velocity in a stimulation method (orthodromic vs antidromic), side of an arm and sex according by age. Method: MABCN conduction studies were performed orthodromically and antidromically in 90 subjects (42 women and 48 men, ranging from 22 to 79 years of age). We divided subjects into three groups by age (group 1: 20-39 years, group 2: 40-59 years, group 3: 60-79 years). The mean sensory nerve action potential amplitudes and sensory nerve conduction velocities in each group was compared by stimulation method, side of an arm and sex. Result: The amplitudes and velocities made a significant difference between orthodromic and antidromic method in all age groups. At comparison in amplitude and velocity by side of an arm, only amplitude was significantly higher in right arm than left by any stimulation method. The amplitudes and velocities were of no statistically differences in sex except amplitude checked orthodromically in right arm. Conclusion: This study suggests that there is the differences in conduction study of MABCN by stimulation method and side of an arm.

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The Influenc on Ambulation of the Difference in Muscle Strength on Hamstring Muscle of Hemiplegic Patients (편마비 환자의 슬건근의 근력의 차이가 보행에 미치는 영향)

  • Yoon, Jang-Soon
    • Journal of Korean Physical Therapy Science
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    • v.12 no.4
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    • pp.69-77
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    • 2005
  • The purpose of this study is to estimate how much the motility of affected and unaffected lower limb respectively would have effects on their ambulation through comparing the difference between their affected and unaffected lower limb and studying the correlation between such difference and their ambulation. In addition, the study also intends to find out remedial measures suitable for improving their ambulation with relevant physical treatment. To do this, a quantitative electromyogram(QEMG) test was done to hamstring of affected and unaffected lower limb so as to yield IP values. Based on such IP values, RMS(root mean square) values as the total sum of IP values were found with QEMG analysis system (made by Medelec Co.) and then the ambulation depending on the difference in muscular strength were analyzed by ink-foot print method as well as the corresponding statistics were processed by T-test through SPSS. The differences in muscular strength of hamstring in unaffected limbs of hemiplegic patients only affect stride length. It was statistically significant. The effect of difference in muscular strength of the hamstring in affected limb of hemiplegic patients on their ambulation was very different between strong and weak group in terms of walking velocity, step per minute, stride and step length, showing statistically significant difference(p<.05). Although there was a difference in the step length of the affected limb, it was not statistically significant(p>.05). For the unaffected hamstring, there were significant differences of stride length between in unaffected limb and in affected limb. For the affected hamstring, there were also significant differences in walking velocity, step per minute, stride and step length. Besides, it was found that the difference of the muscular strength between strong and weak group was at the highest.

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Age and Sex Differences in Nasalance Scores (성별 및 연령에 따른 비음치 비교)

  • 김민정;임성은;최홍식
    • Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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    • v.11 no.2
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    • pp.141-145
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    • 2000
  • Background and Objectives : The nasalance score measured by Nasometer is a supplementary data for the perceptually rated nasality by a trained speech pathologist. The nasalance score varies with subjects. The objective of the present study was to examine whether there are differences in nasalance scores as a function of age and sex. Materials and Method : This study used 20 normal chidren aged from 3 to 8 and 40 normal adults aged from 21 to 37(male : female= 1 : 1) as subjects. The nasalance scores were analyzed in 3 different phonetic contests(nasal, /i/ vowel,/a/ vowel) and 4 different sentence lengths(1, 2, 4, 8 syllable). Results : The children had significantly higher nasalance scores in short sentences an the adults. The female subjects had significantly higher nasalance scores in nasal sentences and in short sentences than the male subjects. Conclusion : These results may indicate that sex and age differences should be considered in the interpretation of the nasalance score in nasal sentences or in short sentences.

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Free-surface Boundary Condition in Time-domain Elastic Wave Modeling Using Displacement-based Finite-difference Method (시간영역 변위근사 유한차분법의 자유면 경계조건)

  • Min Dong-Joo;Yoo Hai Soo
    • Geophysics and Geophysical Exploration
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    • v.6 no.2
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    • pp.77-86
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    • 2003
  • We designed a new time-domain, finite-difference, elastic wave modeling technique, based on a displacement formulation. which yields nearly correct solutions to Lamb's problem. Unlike the conventional, displacement-based, finite-difference method using a node-based grid set (where both displacements and material properties such as density and Lame constants are assigned to nodal points), in our new finite-difference method, we use a cell-based grid set (where displacements are still defined at nodal points but material properties within cells). In the case of using the cell-based grid set, stress-free conditions at the free surface are naturally described by the changes in the material properties without any additional free-surface boundary condition. Through numerical tests, we confirmed that the new second-order finite differences formulated in the cell-based grid let generate numerical solutions compatible with analytic solutions unlike the old second-order finite-differences formulated in the node-based grid set.

Gender Differences in Work-related Musculoskeletal Disorders among Agricultural Workers

  • Kim, Yu-Chang;Shin, Yong-Seok
    • Journal of the Ergonomics Society of Korea
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    • v.30 no.4
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    • pp.535-540
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    • 2011
  • Objective: The aim of this paper is to survey the gender differences Work-related musculoskeletal disorders among agriculture workers. Background: The number of occupational injuries has been decreasing trend in Korea, but it has been increasing in agriculture. The ratio of women worker shows steady increasing trend among the agricultural worker in Korea. Method: This study investigated through the questionnaire to 358 agricultural workers who are working for agriculture located in Gyeongnam, Gyeongbuk and Jeju. Results: The task types occurring frequently and the weight of a heavy object handled according to the sex were showed statistically significant difference. The estimation of WMSDs patients by sex appeared statistically very significant difference. Conclusion: The prevalence rate of WMSDs in female was about 21 percent higher than the prevalence rate of WMSDs in male. Application: The result of this study will help improvement of work environment and prevention of WMSDs in agricultural work.

The Effect of Clothing Appropriateness on Person Perception (의복의 적절성이 대인지각에 미치는 영향에 관한 연구 -이화여대 학생의 캠퍼스 웨어를 중심으로-)

  • 박성은;임숙자
    • Journal of the Korean Society of Clothing and Textiles
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    • v.19 no.2
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    • pp.264-277
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    • 1995
  • is designed to study the college women's desirable clothing behavior in campus, and to find out the difference in person perception according to appropriate or inappropriate clothing. Detailed object is to find out the following differences according to appropriate and inappropriate clothing in campus: 1) formation of impression 2) inference of value. Addi\ulcorner tionally the difference in person perception according to major, grade and preference group are studied. For data collection, 460 college women who are attending Ewha Woman's University are included, and convenience sampling method is used. Frequency, percentage, mean, factor analysis, t-test, ANDV A. duncan test, correspondent analysis are used for data analysis. The result are as follows: 1) Wearer's impression is devided into four factors: appearence evaluation, personality evaluation, ability and activity. 2) There are significant differences in impression formation and value inference according to situational appropriateness. 3) There are significant differences in person perception according to major, grade and preference group.

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