Introduction

The Health and Safety Executive (HSE), having been made aware of your analysis of the factory accident data, commissions you to analyse further information obtained from a study by the Health and Safety Laboratory (HSL) of workers from the brick and tile industries. The HSE wants to know if there is any cause for concern that the workers may potentially be affected by silicosis (see below). Data for two sectors has been provided which the HSE hope may shed light on any potential problems.

There are two key questions which the HSE require you to address:

• Is there any difference in the health (as indicated by cell damage) of the workers in the two operations?
• What associations exist, if any, between length of service and recorded health effect?

Background

The problem

Brick and tile manufacturing along with many other industrial activities in the ceramics sector use quartz (a form of crystalline silica [CS]), feldspar and china clay as typical raw materials. Fine dusts formed during brick and tile production activities, however, are a potential health hazard. One of the reasons for this is that the smallest particles in fine dusts may contain Respirable Crystalline Silica (RCS) formed from the quartz component of the raw materials. It is known that prolonged and excessive exposure to RCS-containing dusts may cause silicosis, a particular form of pulmonary fibrosis leading to incapacity and premature death. As such the HSE takes the issue seriously and has undertaken a preliminary study via the agency of the HLS to look into any potential problems and it is the results of this study that you are commissioned to analyse.

The use of LDH as a warning sign

Lactate dehydrogenase (LDH) is an intracellular enzyme. It oxidizes lactate in the presence of NADH (reduced form of nicotinamide adenine dinucleotide) or reduces pyruvate in the presence of NAD (oxidised form of NADH). It is used clinically to determine cell damage in a number of organs including heart, liver, muscle and blood. Elevations in LDH release are known to be associated with increased levels of cell membrane permeability and its measurement is therefore considered a good indicator of the extent of cell damage. It is deemed to be a useful indicator of the initial stages of cell damage caused by trauma from introduction of alien particles to cells including RCS-containing dusts. In the data presented herein, LDH release in blood cells has been recorded and the results have been calculated to produce a % cell damage figure.

The study group and the data collected

The HSL in undertaking the study stipulated three key criteria for workers to take part in the study, namely:

• They must not have worked in both brick and tile works.
• They worked in areas of tile or brick production (i.e. not in an office or other areas away from the industrial activity).
• They did not smoke.

From the population satisfying these criteria, a sub-sample of 65 workers were randomly selected for blood testing, 38 from brick operations, and 27 from tile operations.

In the Minitab worksheet the results of the study are shown in 5 columns of data.

C1 - A worker ID, identifying the sector (letter B or T) and the individual (3 digit number)

C2 - The sector in which the employee worked (brick or tile)

C3 - Length of service of each employee in the sector (in years)

C4 - Age of each employee (in years)

C5 – The percentage of damaged cells for each employee as calculated by results of the LDH assay (%)

Your task

As in the first part of your data analysis coursework, you a required to produce a coherent, concise, well presented and well-structured report which informs the HSE whether or not there is genuine evidence of difference in the potential health hazard between workers at the two operations.

Further, you are required to report on whether there is any association between worker length of service in the industry and the potential damage to their health. In concluding the report you cannot assume that the HSE understands statistical methods in detail and you will therefore have to summarise your findings in plain non-technical language. The length of the report should be no longer than 6 pages.

You are expected to:

• introduce the type of question you are facing including hypothesis testing

• produce appropriate descriptive/graphical summaries of the data
• justify your choice and undertake the correct statistical tests
• interpret any p-values and confidence intervals and correlation co-efficients correctly
• arrive at brief and clear conclusions that directly answer the problem
• finally, you are free to explore and will be credited for any further analyses of the data you deem worthy of investigation – are the HSE asking exactly the right questions?

Price: $17.93

Solution: The downloadable solution consists of 7 pages, 1093 words and 5 charts.
Deliverable: Word Document