the horizontal axis number of times the same measurement is incorporated using the math that is the assumption that these measurements are independent and we see that very quickly you can actually flip the probability from being 99% being one observation one state in the world to the other state in the world X 1 versus X 2 so be very careful about that another places might come is like you might maybe have I don't know accelerometer or gyro and the gyro is supposed to measure independently the angular rate of your system but the gyro