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Constructing A Confidence Interval. If not specified set the confidence to 095 95 and the level of significance to 005. N x zcriticalvalue When σ unknown. If the population standard deviation cannot be used then the sample standard deviation s can be used when the sample size is greater than 30. It is calculated using the following general formula.
Continuous data are metrics like rating scales task-time revenue weight height or temperature. If not specified set the confidence to 095 95 and the level of significance to 005. Identify the required formula for the confidence interval. Our confidence interval is reliant on a. Were told to della has over 500 songs on her mobile phone and she wants to estimate what proportion of the songs are by a female artist she takes a simple random sample thats what SRS stands for of 50 songs on her phone and finds that 20 of the song sampled are by a female artist based on this sample which of the following is a 99 confidence interval for the proportion of songs on her phone. For example if you construct a confidence interval with a 95 confidence level you are confident that 95 out of 100 times the estimate will fall between the upper and lower values specified by the confidence interval.
If the population standard deviation cannot be used then the sample standard deviation s can be used when the sample size is greater than 30.
Check conditions calculate and interpret a confidence interval to estimate a population proportionView more lessons or practice this subject at httpwww. You can find the upper and lower bounds of the confidence interval by adding and subtracting the margin of error from the mean. The CONFIDENCE function is a great Excel function to construct the confidence interval for a population mean. If the true population mean were as high as 786 seconds we could still have obtained our sample mean of 494 seconds with a. For the Boston shingles construct a 95 confidence interval for the mean weight. In the case of categorical data we are aiming at estimating a population proportion.