Small Sample Confidence Intervals for Population Mean

When constructing a confidence interval for a small sample (n < 30), which distribution should be used?

T-distribution

in small samples (less than 30) we calculate __ critical value not Z critical value

t critical value

what excel function do we use to calculate EBM directly of small sample?

Confidence.T

if we don’t know sigma (pop st.dev) then we use __

t distribution (t alpha / 2 * sample/sq.rt of N) 

Why can’t we use the normal distribution when the sample size is small and σ is unknown?

either sample size too small to assume normality and sigma is unknown

What two numbers are used to build a confidence interval?

Sample mean and margin of error

What function did the presenter use in Excel to find the t-critical value?

T.INV (t alpha/2)

What are the two methods the presenter used to calculate the Error Bound for the Mean (EBM) in a small sample confidence interval?

1. Using T.INV to find the t-critical value and multiplying it by the standard error

2. Using =CONFIDENCE.T with the sample standard deviation and sample size