When we collect data to be applied to a formula, we talk about accuracy. That is to say, we want the accuracy to be as close to 100% as possible. This involves the accuracies of the instruments used to get the data. This also involves the way the measurement is taken.
Let us say, we have to measure 4 items: A, B, C and D.
Assume that A can be measured correct to 1 decimal place, B correct to 2 decimal places, C correct to 3 decimal places while D correct to the nearest whole number.Then the accuracy of the experiment is not even correct to the nearest whole number.
The problem of using the birth year, month, day and hour to get the correct natal chart is from the birth hour. Yes, we use true solar time to define the birth hour. Since we are using the clock to measure time, we have to take care of the accuracy of the clock, we have to adjust to standard time if there is Dayligh Savings Time. We have to adjust to longitude and we have to take care of the equation of time. All these are in our control.
However, we do not know for sure how and when the birth hour is taken. It may be half an hour after the baby is born as it is very busy in the delivery room.
Well, then the accuracy is not better than half an hour off no matter how careful we have taken care of all other items.
Therefore, there is nothing to boast about how accurate the natal chart is. The ancient astrologers have taught us that if the chart does not reflect the life of a person, then we must examine two other charts.