This document presents research on validating and comparing three ergonomic risk assessment methods - RULA, REBA, and Strain Index - for manual labor jobs under India's MGNREGA program. Data was collected through surveys, video analysis, and applying the risk assessment tools to tasks like digging. Chi-square tests found the tools validly associated with reported pain levels. Agreement between tools was moderate to substantial, showing they capture similar but non-identical risks. The research aims to help identify and reduce work-related musculoskeletal disorders.

1. “VALIDATION AND COMPARISON OF ERGONOMIC RISK
ASSESSMENT METHODS IN MANUAL LABOUR WORK OF
MGNREGA”
Presented by:
Manan Shukla
(2012PMM5265)
Supervisor:
Prof. A. Bhardwaj
DEPARTMENT OF MECHANICAL ENGINEERING
MALAVIYA NATIONAL INSTITUTE OF TECHNOLOGY
JAIPUR
1

2. CONTENT
• INTRODUCTION
• RESEARCH METHODOLOGY
• DATA COLLECTION AND ANALYSIS
• RESULT AND DISCUSSION
• CONCLUSION

3. INTRODUCTION
• Work related musculoskeletal disorders are a
major concern in many manual labour work
• There are two ways by which WMSDs can be
detected:
1. by those who are trained in the field of
ergonomics
2. By using Ergonomic Risk Assessment Method

4. BACKGROUND OF THE PROBLEM
• MGNREGA was launched in 200 districts on
2.2.2006. Presently, Mahatma Gandhi NREGA
is being implemented in all the notified rural
areas of the country
• After checking the attendance record and
taking survey it has been found that work
related musculoskeletal injuries caused
increase in absenteeism and lose of wages

5. OBJECTIVE OF STUDY
• To determine the prevalence of
musculoskeletal disorders among MGNREGA
workers and implementation and validation of
the ergonomic risk assessment methods.
• To compare the results of ergonomic risk
assessment method by determining the level
of agreement among tools.

6. ERGONOMIC TOOLS USED IN THE
STUDY
• The Ergonomic tools used in this study are
1. Rapid Upper Limb Assessment
2. Rapid Entire Body Assessment
3. Strain Index

7. RAPID UPPER LIMB ASSESSMENT
(RULA)
• RULA (rapid upper limb assessment) is a
survey method developed for use in
ergonomics investigations of workplaces
where work-related upper limb disorders are
reported.
• The method uses diagrams of body postures
and three scoring tables to provide evaluation
of exposure to risk factors.

9. STEPS TO CONDUCT RULA ANALYSIS
• The development of the method for recording
working postures
• Development of the system for grouping the
body part posture scores
• Development of the grand score and action list

10. RULA SCORE SHEET
UPPER ARM
LOWER ARM
WRIST
WRIST TWIST
A
+ + =
B
+ + =
POSTURE
SCORE
(A)
MUSCLE
USE
FORCE
SCORE
C
NECK
TRUNK
LEGS
POSTURE
SCORE
(B)
MUSCLE
USE FORCE
SCORE
D
GRAND
SCORE

11. RAPID ENTIRE BODY ASSESSMENT
(REBA)
• REBA was developed with six main goals:
• Develop a postural analysis system sensitive to
musculoskeletal risksin a variety of tasks.
• Divide the body into segments to be coded individually,
with reference to movement planes.
• Provide a scoring system for muscle activity caused by
static, dynamic, rapid changing or unstable postures.
• Reflect that coupling is important in the handling of loads
but may not always be via the hands.
• Give an action level with an indication of urgency.
• Require minimal equipment-pen and paper method.
(Hignett & McAtamney, 2000, p. 201)

12. REBA SCORING SHEET
GROUP A GROUP B
+ +
+
=
TRUNK
NECK
LEG
USE
TABLE A
LOAD/
FORCE
SCORE
A
R
UPPER ARM
L
R
LOWER ARM
L
R
WRIST
L
L
USE
TABLE A
COUPLING
SCORE
B
SCORE C
ACTIVITY
SCORE
GRAND REBA SCORE

13. STRAIN INDEX
• The Strain Index (SI) was published by Moore
and Garg in 1995. It was designed to be an
objective method of designating the risk for
developing distal upper extremity disorders. It
is not designed to predict disorders outside
the distal upper extremity.

14. SI SCORE
• An SI score is calculated from the
measurement or estimation of six task
variables:
(a)intensity of exertion,
(b) duration of exertion per cycle,
(c) efforts per minute,
(d) wrist posture,
(e) speed of exertion, and
(f) duration of task per day.

15. SI SCORING SHEET

16. RESEARCH METHODOLOGY
• The procedure undertaken for the study is given below
1. Observed the subject for several cycles
2. Fill the Standard Nordic Questionnaire by the
feedback from the worker and it was determined that
there is prevalence of Musculoskeletal Disorder (MSD)
among MGNREGA workers
3. Determined fundamental tasks of the job by recording
it using Flow Process Chart; and confirmed with the
worker that the selection of tasks was indicative of
"normal operations”.
4. Video graphing the fundamental tasks.

17. PROCEDURE (CONTD.)
• The postures selected for analysis were those
identified as the most demanding (awkward
posture and/or force application) at the
workstation.
• Applying RULA, REBA and SI analysis to the
posture selected in order to get the respective
score and then these scores are classified into
low, medium, high and very high risk levels.
• The chi square test is performed

18. PROCEDURE (CONTD.)
• After checking the validity of the ergonomic
risk assessment methods, the comparison is
done between the three methods by
developing 4*4 agreement matrix.
• The level of agreement is determined by the
kappa coefficient analysis.
• Determining the reason for level of
agreement/disagreement between the three
methods.

19. DATA ANALYSIS

20. CATEGORIZATION OF OUTPUTS
• The risk level used for comparing the
ergonomic risk assessment methods are
divided into four categories as shown
(Marie-Ève Chiasson, Daniel Imbeau, Karine Aubry, Alain Delisle, 2012)
Tool Ranges of
Score
Category Assignment Remarks
Low Medium High Very High
Strain Index 0.0625-20+ 1-2.99 3-4.99 5-7 7+ Categories follow 4 levels
of "risk" in Strain Index
RULA 1 to 7 1&2 3&4 5&6 7 Categories follow 4 "action
levels" given in RULA
REBA 1 to 15 1 to 3 4 to 7 8 - 10 11 to 15 Action level 0 and 1
lumped together

21. CHI SQUARE TEST
• The chi-square independence test is used to
find out whether there is an association
between a row variable and column variable
in a contingency table constructed from
sample data
• In the study chi square test has been used to
determine the validity of each ergonomic
assessment tool in manual labour work.

22. NULL/ALTERNATIVE HYPOTHESIS
• The Null Hypothesis and Alternative
Hypothesis taken in this case are
• H0= There is no association between the
given method risk level and the pain and
ache reported by the workers.
• H1= There is association between the given
method risk level and the pain and ache
reported by the worker

23. PROCESSES SELECTED FOR STUDY
• The ergonomic analysis is done on two
process of MGNREGA
1. Digging work
2. Construction of bund
• These processes are selected because
maximum no. of worker who are affected by
WMSDs are from these processes
• 35 Workers from digging work and 30 worker
from bund work are selected for study

24. Assessment of the Validity of RULA in
MGNREGA (Digging) Work
• A tool is considered valid when it measures
what it intends to measure
• In this study basically the predictive validity of
the ergonomic risk assessment methods is
evaluated

25. S.No. Name of
worker
RULA
score
Risk
Level
Pain/No
Pain
S.No. Name of
worker
RULA
score
Risk
Level
Pain/No
Pain
1. MALA 2.0 1.0 No Pain 21 SUSHEELA 5.0 3.0 Pain
2. SAJJO 2.0 1.0 No Pain 22 CHENA
RAM
5.0 3.0 Pain
3. SUNITA 2.0 1.0 No Pain 23 MATA DIN 6.0 3.0 No Pain
4. GHASI 5.0 3.0 Pain 24 HUKUM
SINGH
6.0 3.0 No Pain
5. KAALU 5.0 3.0 Pain 25 VINA 5.0 3.0 No Pain
6. SANJU 5.0 3.0 Pain 26 RAM
JEEVAN
5.0 3.0 No Pain
7. GENDI
BAI
7.0 4.0 Pain 27 JYOTI 5.0 3.0 Pain
8. VIMALA 7.0 4.0 Pain 28 SHAILU 4.0 2.0 No Pain
9. MEENA 7.0 4.0 Pain 29 SHANTI 4.0 2.0 No Pain
10. KAMALA 7.0 4.0 Pain 30 SEEMA 4.0 2.0 No Pain
11. NIRMALA 7.0 4.0 Pain 31 NANKU 4.0 2.0 No Pain
12. NATHU
LAL
7.0 4.0 Pain 32 SEETA
DEVI
4.0 2.0 Pain
13. MOOLI
DEVI
4.0 2.0 Pain 33 MAANA 4.0 2.0 Pain
14. MAINA
BAI
4.0 2.0 Pain 34 REKHA 4.0 2.0 Pain
15. GANGA 4.0 2.0 Pain 35 ASHA BAI 4.0 2.0 Pain
16. PARVATI 6.0 3.0 Pain
17. SHILA 6.0 3.0 Pain
18 KAMLA 3.0 2.0 Pain
19. PAPPU 3.0 2.0 Pain
20. SAVITRI 5.0 3.0 Pain
RULA score and reported pain in “Digging the
pit using “Geti” by operator”

26. RESULT OF CHI SQUARE TEST
TABLE 5.4: Case Processing Summary
Cases
Valid Missing Total
N Percent N Percent N Percent
RISK LEVEL * PAIN/NO
PAIN 70 100.0% 0 .0% 70 100.0%
TABLE 5.5 Chi-Square Tests
Value df
Asymp. Sig. (2-
sided)
Pearson Chi-Square 14.972a 3 .002
Likelihood Ratio 15.572 3 .001
Linear-by-Linear Association 13.578 1 .000
N of Valid Cases 70
a. 0 cells (.0%) have expected count less than 5. The minimum
expected count is 5.80.

27. FIG : Clustered Bar Chart between Reported
Pain & Risk level

28. CHI SQUARE TEST RESULTS FOR RULA
IN BUNDING WORK
Case Processing Summary
Cases
Valid Missing Total
N Percent N Percent N Percent
RISK LEVEL * PAIN/NO
PAIN
60 92.3% 0 0% 60 100.0%
Chi-Square Tests
Value df
Asymp. Sig. (2-
sided)
Pearson Chi-Square 15.264
a
3 .002
Likelihood Ratio 16.878 3 .001
Linear-by-Linear Association 11.969 1 .001
N of Valid Cases 60

29. CHI SQUARE TEST RESULTS FOR REBA
IN BUNDING WORK
Case Processing Summary
Cases
Valid Missing Total
N Percent N Percent N Percent
RISK LEVEL * PAIN/NO
PAIN
60 100.0% 0 .0% 60 100.0%
Chi-Square Tests
Value df
Asymp. Sig. (2-
sided)
Pearson Chi-Square 10.247
a
3 .017
Likelihood Ratio 10.658 3 .014
Linear-by-Linear Association 7.645 1 .006
N of Valid Cases 60

30. CHI SQUARE TEST RESULTS FOR SI
IN BUNDING WORK
Case Processing Summary
Cases
Valid Missing Total
N Percent N Percent N Percent
RISK LEVEL * PAIN/NO
PAIN
60 100.0% 0 .0% 60 100.0%
Chi-Square Tests
Value df
Asymp. Sig. (2-
sided)
Pearson Chi-Square 11.094
a
3 .011
Likelihood Ratio 12.356 3 .006
Linear-by-Linear Association 9.371 1 .002
N of Valid Cases 60
a. 0 cells (.0%) have expected count less than 5. The minimum
expected count is 5.20.

31. Level of Agreement between the RULA & REBA
using Kappa Analysis
• The kappa coefficient is determined using SPSS 16.0 for
windows and the final result of the analysis is as shown
below:
• Since kappa value is coming to be 0.67, it can be inferred
that there is substantial correlation between RULA and
REBA. The p value is also coming out to be p<0.05 which
signifies that the relationship between RULA and REBA is
statistically significant.
Symmetric Measures
Value
Asymp. Std.
Errora Approx. Tb Approx. Sig.
Measure of Agreement Kappa .670 .061 10.849 .000
N of Valid Cases 130

32. • Since kappa value is coming to be 0.474, it can
be inferred that there is moderate agreement
between RULA and SI. The p value is also
coming out to be p<0.05 which signifies that
the relationship between RULA and SI is
statistically significant

33. • Since kappa value is coming to be 0.526, it can
be inferred that there is moderate agreement
between RULA and SI. However the
association is of REBA and SI is stronger as
compared to RULA and SI. The p value is also
coming out to be p<0.05 which signifies that
the relationship between REBA and SI is
statistically significant.

34. RESULTS AND CONCLUSIONS
• RULA and REBA were expected to show the
greatest degree of agreement. Since kappa
value is coming to be 0.67
• The primary reasons for this are
1. The method to take observations are very
similar.
2. The distal upper extremities are evaluated in
the same manner

35. • RULA only allows a wrist posture score of 1 when the
wrist is bent 0° (perfectly straight). A wrist score of 1
for REBA is allowed for extension or flexion up to 15°.
• RULA with just two classes of body balance (leg
postures) produced more discriminatory power
regardless of balanced and unbalanced leg postures, as
compared to SI and REBA with more classes for leg
postures
• Due to above reasons there is more chance that RULA
score will be higher as compared to REBA and SI

36. • The existence of “force exertions” in SI give a
major emphasis to that risk factor while RULA
does not give it a similar weight.
• SI also highlights “force” in three of its six
variables (effort’s intensity, effort’s duration and
efforts per minute).
• RULA presents different “force” scores once the
importance to the application of force below 2kg
is substantial nevertheless the anatomical zone of
force exertion (arm or fingers).

37. • Due to the incorporation of activity score
there is higher level of agreement between SI
and REBA which is not available in case of
REBA
• From above it can be concluded that RULA
and REBA should not be used simultaneously
since level of agreement is higher.

38. FUTURE SCOPE
• Intermediate scores could be compared instead
of just final scores as well as each score or rating
that contributes to the overall score
• It is also recommended to investigate different
cut-points for risk categories for each of the tools
to see if there is another system of dividing the
tools into risk categories that gives a reasonable
amount of agreement