WMSD Risk Reduction Among Grocery Shoppers

WMSDRisk Reduction Among Grocery Shoppers

Abstract - This study created an ergonomically designed double basket shopping cart with a purpose of reducing Work-Related Musculoskeletal Disorders (WMSD) risks to grocery shoppers and clerks. This study proved that the present design of the double basket shopping cart provides pain and discomfort to the grocery shoppers and clerks which can lead to WMSD. It also showed that incorporating ergonomic features on the proposed design of the double basket shopping cart reduce the pain and discomfort to the grocery shoppers and clerks. The study was conducted in Rey-Sal Grocery Store in Cabuyao, Laguna. Code Shoppy Rapid Entire Body Assessment (REBA), NIOSH, Nordic Questionnaire, and surveys were used to determine the pain and discomfort that the grocery shoppers and clerks feel. Statistical Package for the Social Sciences (SPSS) was used to help in the regression analysis of the researchers. Anthropometry was used in the designing the proposed design, to develop the optimal dimensions of the double basket shopping cart for the comfort of the users. 
The proposed design of the double basket shopping cart effectively reduced the pain level and the discomfort of the grocery shoppers and clerks. It eliminates the need for lifting motions of the grocery shoppers due to the new design. The methods that were used were essential in reducing the risk of WMSD to grocery shoppers and clerks. Cost-benefit analysis and Failure Mode and Effect Analysis were also executed to evaluate the proposed double basket shopping cart design financially, its reliability, durability and performance. Keywords - Ergonomics, double basket shopping cart, work-related musculoskeletal disorder, grocery store.

METHODOLOGY 
In order to fulfill the objectives of the study, a pre-test and post-test study has been conducted as a requirement. The study required two types of respondents: grocery clerks and grocery shoppers. Sample size was computed with the use of Slovin’s formula, error tolerance was set to 10%. The sample size was used for gathering surveys, REBA, NIOSH, Nordic Questionnaire, and anthropometric measurements which are needed to assess the current design of the double basket shopping cart. Rapid Entire Body Assessment (REBA) was used in order to determine the risk level of the specific activities done by the grocery clerks and grocery shoppers while using the present design of the double basket shopping cart. NIOSH lifting equation was used to assess the lifting motions done by the grocery shoppers and to compute for the maximum load that can be lifted during the shopping process. While the Nordic questionnaire was used to assesses the pain that the respondent feels on different parts of their body. The pre-test also included conducting of pre-test surveys and gathering of anthropometric measurements of the respondents. 

Anthropometry was used in establishing the optimal dimensions of the proposed double basket shopping cart, 5th, 50th, and 95thpercentiles were considered. The obtained preliminary data was used and analyzed through the use of Statistical Package for the Socials and Sciences (SPSS). The software was a primary tool to test the normality of the anthropometric data and to determine the correlation between two distinct variables. 

The correlation of the gathered data was determined with the use of four tests: Binomial Logistic Regression of one dependent and five independent variables, Spearman’s Rho Coefficient of nominal and scale data, Kendall’s Tau Correlation of nominal and ordinal data, and Phi Coefficient of two nominal data. Binomial Logistic Regression was used to test whether the body parts of the grocery shoppers and clerks can be affected by the characteristics of the double basket shopping cart which are, comfortability, handle height, wheel design, maneuverability, and the height of the base of the double basket shopping cart. Spearman’s Rho Coefficient was used to correlate the pain felt by the respondents with their age, weight of goods they buy, and height. Kendall’s Tau Correlation of nominal and ordinal data was used to correlate the pain felt by the respondents with the characteristics of the double basket shopping cart. Phi Coefficient of two nominal data was used to correlate the pain felt by the respondents with their gender. The post study used the same number of sample size and same set of clerks were assessed for the post study. 

The post study includes the post survey, post REBA, post Nordic Questionnaire, which tested the usage of the proposed double basket shopping cart during the shopping process, stacking process and nesting process. The post study did not require another NIOSH lifting equation due to the proposed design that eliminated the need for lifting motions. The weighted mean average was also used to determine the significant change with the respondents regarding the present and proposed design. A cost-benefit analysis was used to compare the monetary values of the present and proposed design with the non-monetary benefits that each design gives. The Failure Mode and Effects Analysis were used to assess the potential failures in using the proposed double basket shopping as well as what risk should be prioritized.