R语言代写: Analyses of the quality of its products

Data: The Performance Lawn Equipment excel file can be downloaded from the companion website (http://wps.pearsoned.co.uk/ema_ge_evans_bus_2/)

 

4)    Analyses of the quality of its products

PLE collects a variety of data from special studies, many of which are related to the quality of its products, for e.g. the company collects data from functional test performance of its mowers after assembly; results from the past 30 days are given in the worksheet Mower Test. In addition, many in-process measurements are taken to ensure that manufacturing processes remain in control and can produce according to design specifications. The worksheet Blade Weight shows 350 measurements of blade weights taken from the manufacturing process that produces mower blades during the most recent shift. Elizabeth Burke has asked you to study these data from an analytics perspective, and summarize the findings to these questions.

 

  1. For the Mower Test data, what fraction of mowers fails the functional performance test (using all the mower test data)?

 

  1. For the data in Blade Weight worksheet, what is the sampling distribution of the mean, the overall mean, and the standard error of the mean? Is a normal distribution an appropriate assumption for the sampling distribution of the mean?

 

  • Is the process that makes the blades stable over time? Could any of the blade weights be considered outliers, which might indicate a problem with the manufacturing process or materials?

 

5)    Analyses of supplier performance

The company collects data on supplier performance in terms of timeliness of delivery and number of defects in supplied items. Elizabeth would like you to conduct the relevant analyses and summarizing your findings to the following questions.

 

  1. Chart the proportion of on-time deliveries from 2010 to 2014 using the monthly data in the On-time Delivery Has the proportion of ontime deliveries in 2014 significantly improved since 2010?

 

  1. Chart the number of Defects After Delivery from 2010 to 2014 using the monthly data in the Defects After Delivery Has the number of defects after delivery changed significantly over the past 5 years?