Chaitra is a regional manager at Prettva Steel Manufacturing

Chaitra is a regional manager at Prettva Steel Manufacturing, an international manufacturer of small steer products. Their lines include nuts, bolts, screws, pins, washers, anchors and rivets. Chaitra is responsible for plants in Asia, where she oversees 12 separate facilities. Each facility manufactures all seven products, and uses the same industrial processes to do so. As part of a report to be shared at an upcoming executive meeting, Chaitra has pulled production records from her 12 facilities. She needs to report the production level of her plants. She has captured daily production logs (nuts produced per day, screws per day, pins per day, etc.) for each facility. From Chapter 1, Chaitra knows she is conducting a correlational study of her plants. She also knows that these plants have a population mean production level; if she knew the production level of her plants ever day that they ever have or will exist, she could compute this value. Unfortunately, she has no way to collect that information. As she learned in Chapter 5, although she wants to know the mean production level of each item in the population, she must instead rely on samples of those production levels that she can realistically collect. The daily production is likely to vary randomly away from the population mean; in other words, just because Chaitra finds a production rate of 15000 bolts per day at one plant does not necessarily mean this one measurement is representative of all her plants, in general. So which of these numbers will help her produce her report? She has different measurement for each of the seven products produced at each of her 12 plants, along with daily production records for the last month. She knows from Chapter 3 that computing means will give her a better estimate of the central tendency of her daily production records. But then what? Are the means the best number she has available? That doesn’t seem right either. Although she can determine the mean production level her samples, her plants vary a great deal. If she reports a single value, doesn’t that mean she’s telling upper management that her plants are precisely that efficient? Wouldn’t a range of values be more appropriate? If so what range should she use?

Rivets

4340

Find the mean and standard deviation for each data set.

Solution

Variable Mean StDev
Nuts 10748 3168
Bolts 14001 2198
Screws 10975 202
Pins 18014 78.9
Washers 6076.8 301.0
Anchors 4806 1921
Rivets 3755 1854