Linear Equations · Exercise 9

Use the following information to answer the next exercise. contains real data for the first two decades of flu reporting.
$$\begin{array}{ccc}\text{Year}& \text{Number of Flu Cases Diagnosed}& \text{Number of Flu Deaths}\\ \text{Pre-1981}& \text{91}& \text{29}\\ \text{1981}& \text{319}& \text{121}\\ \text{1982}& \text{1,170}& \text{453}\\ \text{1983}& \text{3,076}& \text{1,482}\\ \text{1984}& \text{6,240}& \text{3,466}\\ \text{1985}& \text{11,776}& \text{6,878}\\ \text{1986}& \text{19,032}& \text{11,987}\\ \text{1987}& \text{28,564}& \text{16,162}\\ \text{1988}& \text{35,447}& \text{20,868}\\ \text{1989}& \text{42,674}& \text{27,591}\\ \text{1990}& \text{48,634}& \text{31,335}\\ \text{1991}& \text{59,660}& \text{36,560}\\ \text{1992}& \text{78,530}& \text{41,055}\\ \text{1993}& \text{78,834}& \text{44,730}\\ \text{1994}& \text{71,874}& \text{49,095}\\ \text{1995}& \text{68,505}& \text{49,456}\\ \text{1996}& \text{59,347}& \text{38,510}\\ \text{1997}& \text{47,149}& \text{20,736}\\ \text{1998}& \text{38,393}& \text{19,005}\\ \text{1999}& \text{25,174}& \text{18,454}\\ \text{2000}& \text{25,522}& \text{17,347}\\ \text{2001}& \text{25,643}& \text{17,402}\\ \text{2002}& \text{26,464}& \text{16,371}\\ \text{Total}& \text{802,118}& \text{489,093}\end{array}$$

Use the columns Year and Number of Flu Cases Diagnosed. Why is year the independent variable and number of flu cases diagnosed the dependent variable (instead of the reverse)?

OpenStax, Statistics · §12.1 Linear Equations · Exercise 9