MBTI and the MBTI test are two different things although often confused as one.
If you want to be scientific, then a more accurate statement is:
The MBTI test, may have weak validity and precision across all it's dichotomies.
Albeit even this matter seems to be contended.
"CPP Inc., the publisher of the MBTI instrument, calls it "the world's most widely used personality assessment",with as many as two million assessments administered annually. The CPP and other proponents state that the indicator meets or exceeds the reliability of other psychological instruments and cite reports of individual behavior. Some studies have found strong support for construct validity, internal consistency, and test-retest reliability, although variation was observed. However, some academic psychologists have criticized the MBTI instrument, claiming that it "lacks convincing validity data". Some studies have shown the statistical validity and reliability to be low. The use of the Myers-Briggs Type Indicator as a predictor of job success has not been supported in studies,[15][16] and its use for this purpose is expressly discouraged in the Manual.[17]"
If you want to be scientific, then a more accurate statement is:
The MBTI test, may have weak validity and precision across all it's dichotomies.
Albeit even this matter seems to be contended.
"CPP Inc., the publisher of the MBTI instrument, calls it "the world's most widely used personality assessment",with as many as two million assessments administered annually. The CPP and other proponents state that the indicator meets or exceeds the reliability of other psychological instruments and cite reports of individual behavior. Some studies have found strong support for construct validity, internal consistency, and test-retest reliability, although variation was observed. However, some academic psychologists have criticized the MBTI instrument, claiming that it "lacks convincing validity data". Some studies have shown the statistical validity and reliability to be low. The use of the Myers-Briggs Type Indicator as a predictor of job success has not been supported in studies,[15][16] and its use for this purpose is expressly discouraged in the Manual.[17]"
http://en.wikipedia.org/wiki/Myers-Briggs_Type_Indicator