33.6 Exercises

Selected answers are available in Sect. D.30.

Exercise 33.1 A study evaluated various food mixtures for sheep (Moir 1961). Describe the scatterplot (Fig. 33.6) in terms of the form of the relationship, the direction of the relationship (if relevant), and the variation in the relationship.

FIGURE 33.6: Scatterplots for the sheep-food data

Exercise 33.2 A study examined the direct current generated by a windmill and its association with wind speed (Joglekar et al. 1989; Hand et al. 1996). Describe the relationship (Fig. 33.7).

FIGURE 33.7: The relationship between DC output and wind speed

Exercise 33.3 A study examined the mandible length and gestational age for 167 foetuses from the 12th week of gestation onward (Royston and Altman 1994). How would you describe the relationship (Fig. 33.8)?

FIGURE 33.8: The relationship between gestational age and mandible length

Exercise 33.4 A study examined the time taken to deliver soft drinks to vending machines (Montgomery and Peck 1992). How would you describe the relationship (Fig. 33.9)?

FIGURE 33.9: The time taken to deliver soft drinks to vending machines

References

Hand DJ, Daly F, Lunn AD, McConway KY, Ostrowski E. A handbook of small data sets. London: Chapman; Hall; 1996.

Joglekar G, Scheunemyer JH, LaRiccia V. Lack-of-fit testing when replicates are not available. The American Statistician. 1989;43:135–43.

Moir RJ. A note on the relationship between the digestible dry matter and the digestable energy content of ruminant diets. Australian Journal of Experimental Agriculture and Animal Husbandry. 1961;1:24–6.

Montgomery DC, Peck EA. Introduction to regression analysis. New York: Wiley; 1992.

Royston P, Altman DG. Regression using fractional polynomials of continuous covariates: Parsimonious parametric modelling. Journal of the Royal Statistical Society, Series C. 1994;43(3):429–67.