Ruby Tuesday Altman Z-Score, Current: 2.57Altman Z-Score, 2009: 2.57Ruby Tuesday ( RT) is the least risky of the group, with a Z-Score of 2.57 for the last 12 months, flat from the previous year. But the casual restaurant chain remains on shaky ground. In its recent quarterly report, Ruby Tuesday posted a decline in year-over-year revenues, booking a 1.2% drop in sales to $313.5 million, missing expectations by just under $1 million. The softening was primarily driven by the shuttering of 16 company-owned restaurants in its fiscal-fourth quarter compared with the year-earlier period. The all-important metric of same-store sales, also known as comps, which measure sales at well-established stores open at least one year, grew just 0.3% at Ruby Tuesday-owned restaurants last quarter, while franchised locations saw same-store sales drop 0.5%. Even so, Ruby Tuesday's profits grew by healthy percentages and earnings of $21 million, or 33 cents per share, easily beat Wall Street's expectations. The casual restaurant chain also forecast disappointing fiscal 2011 earnings per share in a range of 76 cents to 86 cents, and cautioned that its operating margins would be down for the year as it invests more money into a higher-quality menu and new product offerings.