Tiffany Dolsing, a market analyst at the market research firm of Sanders & Sons, is analyzing household budget data collected by her firm. Tiffany's dependent variable is monthly household expenditures on groceries (in $'s), and her independent variable is annual household income (in $1,000's). Regression analysis of the data yielded the following tables.

	Coefficients	Standard Error	t Statistic	p-value
Intercept	39.14942	22.30182	1.755436	0.109712
x	-1.792312	0.407507	4.398234	0.001339

Source	df	SS	MS	F		s.e. = 29.51443
Regression	1	16850.99	16850.99	19.34446		r2 = 0.682478
Residual	9	7839.915	871.1017
Total	10	24690.91

The correlation coefficient between the two variables in this regression is __________.