Chapter 3 Normal Data

Example 3.1 Diameters of 40 keys for a keyboard. The data are used to illustrate the statistical analysis of a single normal sample. Example 2.4 Contents of Cu, Zu, and Pb in geochemical prospecting. The data are used to illustrate the statistical analysis of a single normal sample. Example 2.5 Reaction times for two groups of flies exposed to different levels of a nerve gas. The example illustrates the statistical analysis of two normal samples with a common variance. Example 3.2 Diameters of clams Protothaca staminea sampled above and below the tide line. The data illustrate the statistical analysis of two normal samples with different variances. Example 3.3 Four groups of soys bean plants that are exposed to different treatments. The response is total area of the leaves. The data are used to introduce the statistical analysis of more than two normal samples. Example 3.4 Recordings of systolic blood pressure and age for two professions. The data are used to illustrate linear regression analysis. Example 3.5 Remaining mass of sand in a sieve as a function of the number of rotations. The data are used to illustrate the test for linear regression. Exercise 3.1 In online monitoring of production of keys for a keyboard, keys were sampled. The weight in milligrams of a sample of 15 keys is considered in the exercise. Exercise 3.2 Two measurement methods used to determine the content of CaO in pieces of rock are being compared. For this purpose the content of CaO in nine pieces of rock has been determined by both methods. Exercise 3.3 It is often argued that when measurements of a physical quantity are repeated twice by the same person, there is a tendency that the first result influences the second one. This exercise considers the data from an experiment designed to investigate this allegation. Exercise 3.4 In an attempt to quantify the pollution, the content of SO2 (in ppm) in the air has been measured in a rural area and in an urban area. Exercise 3.5 Prediction intervals. No data for this exercise. Exercise 3.6 The data in this exercise is part of a larger investigation of caries among school children and consist of the observed number of DMF teeth (Damaged, Missing, or Filled) of 12-year-old boys. The purpose of the investigation is to shed light on the assumption that a high natural content of fluoride in the water will diminish the number of DMF teeth. The investigation was conducted in the 1960s before fluoride was allowed to be added to toothpaste in Denmark. Exercise 3.7 The data for this exercise are from a study of the Noble fir seed chalcid Megastimus pinus. Exercise 3.8 Data for this exercise is part of a larger investigation of the occurrence of fungi in the soil of the moor, and in particular a group of fungi which grows on the roots of the heather and is called Mykorrhiza.