Statistics (Week 7) Assignment

Problem Set 2 : Chapter 9 1

Population standard deviation (or population variance ) and sample standard deviation (or sample variance ) determines whether we should use a z-score or a t statistics for a hypothesis test . If population variance is known than we should use z-score for a hypothesis test . If population variance is unknown and variance is estimated using sample data than we should use t statistic for a hypothesis test 2

By increasing the variability of the scores , the estimated standard error in the denominator will increase and the effect would be

to decrease the value of t (close to zero

By increasing the number of scores in the sample , the estimated standard error in the denominator will decrease and the effect would be to increase the value of t (farther from zero

By increasing the difference between the sample mean and the population mean , the numerator will increase and the effect would be to increase the value of t (farther from zero 5

M 45 , SS 960 , and n 16 The standard deviation measures the variability of the sample data and it is an estimate of population standard deviation . The estimated standard error measures the variability of the sampling distribution of the mean . In other words , the estimated standard error is the standard deviation of the sample mean estimate of a population mean 13 100 , M 121 , SS 600 , and n 16 .01 is given

The degree of freedom is n - 1 16 - 1 15

At .01 level of...