Margin of Error :Margin of Error & Confidence Intervals headlessprofessor


When this applies :When this applies A sample is being used to estimate a population mean


What it tells you :What it tells you How far off your estimate is likely to be


What you need :What you need Sample size = N


What you need :What you need Sample size = N Sample mean


What you need :What you need Sample mean & N Standard deviation


What you need :What you need Sample mean & N Standard deviation Z score for level of confidence


What you need :What you need Sample mean & N Standard deviation Z score for level of confidence (z = 1.96)


How to Calculate :How to Calculate Standard Deviation Divided by Square Root Of Sample Size


How to Calculate :How to Calculate Standard Deviation Divided by Square Root Of Sample Size (standard error)


How to Calculate :How to Calculate Margin of Error = Standard Error times Z score


Example :Example N = 49 Mean = 78 Std Dev = 5 Z score = 1.96


How to Calculate :How to Calculate Square root of sample size = Square root of 49 = 7


How to Calculate :How to Calculate Standard deviation divided by square root of sample size 5 / 7


How to Calculate :How to Calculate Standard deviation divided by square root of sample size 5 / 7 = 0.714


How to Calculate :How to Calculate Standard deviation divided by square root of sample size 5 / 7 = 0.714 Standard Error


How to Calculate :How to Calculate Standard deviation divided by square root of sample size 5 / 7 = 0.714 Standard Error


How to Calculate :How to Calculate Margin of Error = Std Error X Z 0.714 X 1.96


How to Calculate :How to Calculate Margin of Error = Std Error X Z 0.714 X 1.96 = 1.40


What this means :What this means Margin of Error: 95% of the time, the population mean will be within 1.40 of the mean


Confidence Interval :Confidence Interval The range of scores from mean – ME to mean + ME


Example of Confidence Interval :Example of Confidence Interval The range of scores from 78 – 1.40 to 78 + 1.40


Example of Confidence Interval :Example of Confidence Interval The range of scores from – 1.40 to 78 + 1.40 76.6 to 79.4


To get narrower :To get narrower Have a lower standard deviation


To get narrower :To get narrower Have a lower standard deviation Accept a lower level of confidence (e.g., .90 instead of .95)


To get narrower :To get narrower Have a lower standard deviation Accept a lower level of confidence (e.g., .90 instead of .95) Use a larger sample size N


To get a better level of confidence :To get a better level of confidence Have a lower standard deviation


To get a better level of confidence :To get a better level of confidence Have a lower standard deviation Accept a broader confidence interval


To get a better level of confidence :To get a better level of confidence Have a lower standard deviation Accept a broader confidence interval Use a larger sample size


Use T instead of Z :Use T instead of Z When population SD is not known


Use T instead of Z :Use T instead of Z When population SD is not known Use df = N - 1


Margin of Error :Margin of Error & Confidence Intervals headlessprofessor