"Save lives" arguments might not be as effective as you think: A randomized field experiment on blood donation.

OBJECTIVES: Many communication campaigns to encourage people to give blood rely on "save lives" messages, even though there is no experimental evidence as to the effectiveness of this kind of argument with respect to blood donation. The objective of this study is to test experimentally if it is indeed an effective way to prompt people to give blood, in order for communication campaigns to be evidenced-based. METHODS: One thousand and twenty-two lapsed blood donors were sent, at random, either a standard letter or the same letter containing an additional "save lives" message. The blood donation center measured intention to donate and actual donor return rate (3%) after 10months. RESULTS: Although fewer people in the "save lives" condition said they had no intention to give blood again, the "save lives" letter did not lead to more donor returns than the standard letter. CONCLUSIONS: Our results suggest that contrary to intuition, campaigns to promote blood donation should not rely blindly on "save lives" arguments.

The Spectroscopic Orbit of the Planetary Companion Transiting HD 209458.

We report a spectroscopic orbit with period P=3.52433+/-0.00027 days for the planetary companion that transits the solar-type star HD 209458. For the metallicity, mass, and radius of the star, we derive [Fe/H&sqbr0;=0.00+/-0.02, M*=1.1+/-0.1 M middle dot in circle, and R*=1.2+/-0.1 R middle dot in circle. This is based on a new analysis of the iron lines in our HIRES template spectrum and also on the absolute magnitude, effective temperature, and color of the star, and it uses isochrones from four different sets of stellar evolution models. Using these values for the stellar parameters, we reanalyze the transit data and derive an orbital inclination of i=86&fdg;1+/-1&fdg;6. For the planet, we derive a mass of Mp=0.69+/-0.05 MJup, a radius of Rp=1.40+/-0.17 RJup, and a density of rho=0.31+/-0.07 g cm-3.