Astrology can be extremely accurate. But, it is only as accurate as your birth time, which is used to calculate not only the planetary positions, but also your Ascendant (Rising Sign), to the exact degree and minute. That calculation then determines the degree on the Midheaven and all of the house cusps. The cusps then determine in which house your planets will fall. Without an accurate birth time, interpretations and forecasts are invariably incorrect. All of this information is then used in interpreting your personality, determining your career choices, comparing and contrasting your chart with those of other people you know, and forecasting events in your life.
Before you schedule a consultation or order charts and reports, you should obtain a copy of your birth certificate. If you do not have a birth certificate, if the time is not stated on yours, if you suspect your birth certificate is in error, or if you have only an estimated birth time, you can have your chart rectified (see next section).
But what about your birth certificate? How accurate is it? It may not be as accurate as you think. It's not hard to get the date and the place correct, but birth times are an entirely different story. Since doctors and nurses are not usually astrologers, they give little attention to the exact time of birth. For example, they may round off an 8:38 birth time to 8:40 or 8:35. A doctor may fill out the birth certificate later on and use an estimated birth time that could be far earlier or later than the true time of birth, or then the time recorded on the delivery room records.
Depending on where and when you were born, your birth certificate may not even have a space for the time of birth. Some people have no written birth certificates at all because they were born at home, or during times when birth certificates were not considered necessary, or in countries where birth certificates are or were not issued. Some parts of the United States have other problems with birth certificate times. For example, during certain years in the state of Illinois, War Time, the precursor to our modern Daylight Savings Time, was in effect but was not observed by all hospitals, many of which continued to operate on Standard Time. That means that if you happen to have been born in Illinois during those times, your birth certificate could be off by an entire hour.
Without an exact birth time, astrology in general, and predictive astrology in particular, are rarely accurate. There may be some general information and interpretations that are correct, but the subtleties and events-oriented aspects will be wrong.