On February 15, 1991, President George H. W. Bush traveled to Raytheon's Patriot manufacturing plant in Andover, Massachusetts, during the Gulf War, he declared, the "Patriot is 41 for 42: 42 Scuds engaged, 41 intercepted!"
The President's claimed success rate was thus over 97% to that point in the war.

On April 7, 1992 Theodore Postol of the Massachusetts Institute of Technology, and Reuven Pedatzur of Tel Aviv University testified before a House Committee stating that, according to their independent analysis of video tapes, the Patriot system had a success rate of below 10%, and perhaps even a zero success rate.

Also on April 7, 1992, Charles A. Zraket of Harvard's Kennedy School of Government and Peter D. Zimmerman of the Center for Strategic and International Studies testified about the calculation of success rates and accuracy in Israel and Saudi Arabia and discounted many of the statements and methodologies in Postol's report.

According to Zimmerman, it is important to note the difference in terms when analyzing the performance of the system during the war:
Success Rate – the percentage of Scuds destroyed or deflected to unpopulated areas
Accuracy – the percentage of hits out of all the Patriots fired
In accordance with the standard firing doctrine on average four Patriots were launched at each incoming Scud – in Saudi Arabia an average of three Patriots were fired.
The large number of missiles fired suggests low confidence in individual missiles and a higher rate of successful interceptions was achieved through brute force.
For example, if a Patriot has a 50% individual success rate, two missiles will intercept 75% of the time, and three will intercept 87.5% of the time.
Only one has to hit for a successful interception, but this does not mean that the other missiles would not also have hit.

The Iraqi redesign of the Scuds also played a role.
Iraq had redesigned its Scuds by removing weight from the warhead to increase speed and range, but the changes weakened the missile and made it unstable during flight, creating a tendency for the Scud to break up during its descent from near space.
This presented a larger number of targets as it was unclear which piece contained the warhead.

According to the Zraket testimony there was a lack of high quality photographic equipment necessary to record the interceptions of targets.
 Therefore, Patriot crews recorded each launch on standard definition videotape, which was insufficient for detailed analysis.
Damage assessment teams videotaped the Scud debris that was found on the ground, and crater analysis was then used to determine if the warhead was destroyed before the debris crashed or not.
Furthermore, part of the reason for the 30% improvement in success rate in Saudi Arabia compared to Israel is that the Patriot merely had to push the incoming Scud missiles away from military targets in the desert or disable the Scud's warhead in order to avoid casualties, while in Israel the Scuds were aimed directly at cities and civilian populations.
The Saudi Government also censored any reporting of Scud damage by the Saudi press.
The Israeli Government did not institute the same type of censorship.
Furthermore, Patriot's success rate in Israel was examined by the IDF (Israel Defense Forces) who did not have a political reason to play up Patriot's success rate.
The IDF counted any Scud that exploded on the ground (regardless of whether or not it was diverted) as a failure for the Patriot.
 Meanwhile, the U.S. Army who had many reasons to support a high success rate for Patriot, examined the performance of Patriot in Saudi Arabia.

Both testimonies state that part of the problems stem from its original design as an anti-aircraft system.
Patriot was designed with proximity fuzed warheads, which are designed to explode immediately prior to hitting a target spraying shrapnel out in a fan in front of the missile, either destroying or disabling the target.
These missiles were fired at the target's center of mass.
 With aircraft this was fine, but considering the much higher speeds of TBMs, a
On February 15, 1991, President George H. W. Bush traveled to Raytheon's Patriot manufacturing plant in Andover, Massachusetts, during the Gulf War, he declared, the "Patriot is 41 for 42: 42 Scuds engaged, 41 intercepted!" The President's claimed success rate was thus over 97% to that point in the war.
On April 7, 1992 Theodore Postol of the Massachusetts Institute of Technology, and Reuven Pedatzur of Tel Aviv University testified before a House Committee stating that, according to their independent analysis of video tapes, the Patriot system had a success rate of below 10%, and perhaps even a zero success rate.
Also on April 7, 1992, Charles A. Zraket of Harvard's Kennedy School of Government and Peter D. Zimmerman of the Center for Strategic and International Studies testified about the calculation of success rates and accuracy in Israel and Saudi Arabia and discounted many of the statements and methodologies in Postol's report.
According to Zimmerman, it is important to note the difference in terms when analyzing the performance of the system during the war:
Success Rate – the percentage of Scuds destroyed or deflected to unpopulated areas
Accuracy – the percentage of hits out of all the Patriots fired
In accordance with the standard firing doctrine on average four Patriots were launched at each incoming Scud – in Saudi Arabia an average of three Patriots were fired. The large number of missiles fired suggests low confidence in individual missiles and a higher rate of successful interceptions was achieved through brute force. For example, if a Patriot has a 50% individual success rate, two missiles will intercept 75% of the time, and three will intercept 87.5% of the time. Only one has to hit for a successful interception, but this does not mean that the other missiles would not also have hit.
The Iraqi redesign of the Scuds also played a role. Iraq had redesigned its Scuds by removing weight from the warhead to increase speed and range, but the changes weakened the missile and made it unstable during flight, creating a tendency for the Scud to break up during its descent from near space. This presented a larger number of targets as it was unclear which piece contained the warhead.
According to the Zraket testimony there was a lack of high quality photographic equipment necessary to record the interceptions of targets.  Therefore, Patriot crews recorded each launch on standard definition videotape, which was insufficient for detailed analysis. Damage assessment teams videotaped the Scud debris that was found on the ground, and crater analysis was then used to determine if the warhead was destroyed before the debris crashed or not. Furthermore, part of the reason for the 30% improvement in success rate in Saudi Arabia compared to Israel is that the Patriot merely had to push the incoming Scud missiles away from military targets in the desert or disable the Scud's warhead in order to avoid casualties, while in Israel the Scuds were aimed directly at cities and civilian populations. The Saudi Government also censored any reporting of Scud damage by the Saudi press. The Israeli Government did not institute the same type of censorship. Furthermore, Patriot's success rate in Israel was examined by the IDF (Israel Defense Forces) who did not have a political reason to play up Patriot's success rate. The IDF counted any Scud that exploded on the ground (regardless of whether or not it was diverted) as a failure for the Patriot.  Meanwhile, the U.S. Army who had many reasons to support a high success rate for Patriot, examined the performance of Patriot in Saudi Arabia.
Both testimonies state that part of the problems stem from its original design as an anti-aircraft system. Patriot was designed with proximity fuzed warheads, which are designed to explode immediately prior to hitting a target spraying shrapnel out in a fan in front of the missile, either destroying or disabling the target. These missiles were fired at the target's center of mass.  With aircraft this was fine, but considering the much higher speeds of TBMs, a
MIM-104 Patriot