USAMO

Preliminary List - April 30, 2008

Official emails with the official invitation will start going out no later than Friday, April 11, 2008. Paper postal invitations will be mailed shortly thereafter. Please see the reminder in Section V, page 5 of the AIME Teachers' Manual, no AIME results will be given out by phone (or otherwise) until after April 13. Please do not call or contact us now, we have much to do yet.

We expect to begin mailing AIME reports this week, either April 8 or April 9. Again, please do not call or email until after April 13.

SELECTION

The first USAMO Selection Index for students who took the AMC 12 (either A-date or B-date is 204.0. This yields 320 students.

The lowest AIME score among these students was 6 (144.0 + 10*6) so now we look at all students in 10th grade and below who got a 6 or better on the AIME. There are 468 of them, so we need to use the USAMO Index to discriminate among them.

The 156 highest USAMO indices among them are at Index 202.5 and higher.

This gives 476 students first selected to the USAMO. To them we add 10 students from U.S. States not already represented. This gives us 486 invited to take the USAMO.

We still have some late AIME II papers coming in. We anticipate about another 10 invitees from these late papers, and some U.S. citizens living abroad. When all is said and done, we will have between 495 and 500 students invited to 2008 USAMO.

As a statistical aside, we did a correlation between indices and USAMO score using 2007 data.

• The correlation between AIME score and USAMO score is 0.40
• The correlation between USAMO Index and USAMO score is 0.45
• The USAMO is a slightly better predictor according to that analysis.