Quality Control For Allrepairs Mechanics

By Author: Anthony W Bills
Total Articles: 158
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Quality control for AllRepairs mechanics
Executive Summary
Presenting of results from an engineering company has been contentious. The paper will present how to get results from research investigating the efficiency and effectiveness of the mechanics at AllRepairs in terms of the time that they take in carrying out the repairs. In AllRepairs, a dispatcher evaluates every job lodged on the basis of how difficult it is likely to be and then assigns one of their four mechanics to the job. In this research, the Human Resources Department provided information on how long any employee has been with the company. All mechanics keep time sheets that allow data to be collected on time spent on each repair job.
Data was collected from the branch of AllRepairs that provides mechanics to repair refrigerators and from by randomly selecting a sample of 293 jobs which were done last year. In order to get data on the level of satisfaction of the customers, a survey was carried out on the associated customers. This report shows the analysis of the data and the results obtained from the data by the Dynamic Econometric Consulting ...
... Services (DECS) consultants. The mechanics were found to be becoming more efficient and were spending less time as they gained experience.

Introduction
AllRepairs is a firm that offers a wide range of repair services for households and businesses. Like any other business enterprise, AllRepairs needs efficient staffs who work effectively. The company has a policy of systematically reviewing all branches of their organization in order to maintain a high quality of service and to isolate any inefficiency in the provision of the various services they provide. For this particular purpose, the company contracted Dynamic Econometric Consulting Services (DECS) to evaluate the efficiency of the repair staff as measured by the time it takes them to undertake their assigned jobs. In particular, DECS was supposed to find evidence of any marked differences across staff undertaking the same tasks (Hand et al 1991).
In order to maintain good relationship with customers and maximize the chances of repeat jobs, AllRepairs has been engaging consultants to conduct customer satisfaction surveys in the past. From these previous surveys, the company has set 80% as the target for either satisfied or very satisfied customers. DECS was supposed to use statistical analysis to determine whether this was the case in the refrigerator repair branch. The results showed that there is marked difference across the mechanics of the company. The results showed that the efficiency of the mechanics depended on the experience gained by the workers as they worked with the company. Eighty percent of the customers are either satisfied or very satisfied with the surfaces of the mechanics (Erlebacher 1999).
Literature review
Key Points
• The least time taken to complete a repair job was 6 minutes and the maximum was 107 minutes and the overall average time was 32.642 minutes.
• The average time for mechanic 1 was 31.36 minutes.
• The average time for mechanic 2 was 39.683 minutes.
• The average time for mechanic 3 was 32.027 minutes.
• The average time for mechanic 4 was 28.875 minutes.
• The average time for job difficulty level 1 was 20.024 minutes.
• The average time for job difficulty level 2 was 35.011 minutes.
• The average mean time for job difficulty level 3 was 51.212 minutes.
The results show that average times per job across the mechanics vary from 28.875 minutes to 39.683 minutes.
Relationship between the average time per job and the experience of the mechanic
Experience (years) Average Time (min.)
Mechanic 1 12 31.360
Mechanic 2 10 39.683
Mechanic 3 9 32.027
Mechanic 4 2 28.875

Relation between experience and the time consumed to complete the job
The chart above shows that there is a correlation between the number of years of experience of a mechanic and the average time taken to complete a job. Mechanics with more working experience in AllRepairs generally complete their repair jobs in less time than those with less experience. This implies that the more a mechanic works with the company, the more efficient he/she becomes (Hand et al 1991).
Class Interval Mid-Point x Frequency f
0- 10 5 5
11-020 15.5 53
21- 30 25.5 82
31- 40 35.5 81
41- 50 45.5 49
51- 60 55.5 11
61- 70 65.5 4
71- 80 75.5 5
81- 90 85.5 0
91- 100 95.5 1
101-110 105.5 1
Table above shows the relation of time spent in class and the possible outcome of the job done
From the collected data, 227 customers either said that they were satisfied or very satisfied with the way the job was done. In order to find out if our data supports 80% level of satisfied and very satisfied customers, we will let x be the proportion of the satisfied and very satisfied customers. The null hypothesis Ho: x = 0.8 is tested against the alternative hypothesis: Ha: x is not equal to 0.8.
If we take the customers who said that they were either satisfied or very satisfied to be OK and all the other customers to be NOT OK, then the variables become a binomial setting with N = 293 and x = 0.8.
x is the proportion of OK jobs in the sample of 293.
If Ho is true then the variable x will approximate normal distribution with mean = 0.8 and standard deviation = SQRT [(0.8) (0.2)/293] = 0.023.
The mean of the sample, expressed as a proportion of the total is (32.642/293) = 0.111.
If Ho is true, the associated z score is 4.807.
Testing 5% level of significance, the critical Z scores are z>2.0167and z