Proportion Z Interval Calculator

Confidence Interval for Population Proportion.

 

Example

Find the 0.99 confidence interval for 2048 successes in 4040 trials.

Value	Keystroke	Display	Description
.99	C Level	0.99	Stores the C Level value.
4040	n	4040	Stores the n value.
2048	÷ ROLL p̂	0.5069	Stores the  p̂ value.
	Z Int	0.04052	Calculates the Z Interval

The keystrokes '÷ ROLL p̂' are in CHN calculation mode. Since the 4040 value was just entered, tapping 'ROLL' saves you from having to re-enter the n value.
In ALG calculation mode, the keystrokes would be '÷ rgx p̂'.
In RPN calculation mode, the keystrokes would be 'SWAP ÷ STO p̂'.

This calculator also calculates the upper and lower limits and enters them in the stack.
By returning these values to the stack you can use them for other calculations without having to write them down and re-enter them.

Value	Keystroke	Display	Description
	ROLL	0.4867	The lower limit
	ROLL	0.5272	The upper limit

The History Detail

Proportion Z Interval
         0.5272 : The upper limit.
         0.4867 : The lower limit.
           0.99 : The confidence level.
          4,040 : The number of trials, n.
         0.5069 : The proportion estimate, p̂.
        0.04052 : The Confidence Interval for Population Proportion..

Note that you can enter a "Z Int" value and solve for the C Level, n or p̂.

Reference:

Confidence Interval - Wikipedia