Error Analysis/Significant Figure help please!! Hi Physics Forums, I have an assignment due very soon and I have completed everything, bar error analysis. I have been told that we need to calculate relative and absolute errors or something along those lines and I have NO IDEA what im doing. I have been researching the topic and searching forum threads, but to no avail. Please someone help me! Basically, I have calculated the local acceleration of gravity via a pendulum experiment. I have measured various lengths of fishing line which I have dropped and recorded the time of 5 periods for. I have plotted the average period for 5 different lengths of fishing line, squared (T²) against the lengths of the fishing line (L). I have measured the average period to 4 significant figures (e.g 4.033, 4.267 etc) and the length to two significant figures (e.g 4.0, 4.5, 5.0) etc. The lengths were measured using a tape measure with 10cm intervals and the stopwatch used to record the period had 2 decimal places. (Although the stopwatch only had 2 decimal places, the period values have 3 decimal places as they were recorded based on 15 periods and then divided by 15, so the 15 periods had 2 decimal places but 4 significant figures). How on earth do I do an error analysis?? Any help would be great. Thanks.