Question

According to General Social Survey of 2016, the population distribution of number of years of education for self-employed individuals in the United States has a mean of 12.9 and a standard deviation of 4.0. The distribution is skewed slightly to the right. For each sample size below: Describe the mean, standard error, and shape of the sampling distribution of the means for a random sample of: (7 pts) a) 16 residents b) 49 residents c) 121 residents Describe the pattern as n increases

Answer 1

a) Mean is 12.9

b) Standard Error

i) n = 16, Standard Error = 1

The shape of the sampling distribution means is not normal

ii) n = 49 , Standard Error = 0.5714285714

The shape of the sampling distribution means is normal

iii) n = 121, Standard Error = 0.3636363636

The shape of the sampling distribution means is normal

c)Describe the pattern as n increases

As the number of random samples(n) increases the value for the standard error decreases

Explanation:

Central Limit Theorem states that

if the sample size is large (generally n ≥ 30), and the standard deviation of the population is finite, then the distribution of sample means will be approximately normal.

a) 16 residents

Mean = 12.9

Standard Error = Standard Deviation /√n

= 4/√16

= 4/4

= 1

n < 30, hence, The shape of the sampling distribution means is not normal

b) 49 residents

= Mean = 12.9

Standard Error = Standard Deviation /√n

= 4/√49

= 4/7

= 0.5714285714

n > 30, hence, The shape of the sampling distribution means is normal

c) 121 residents

Mean = 12.9

Standard Error = Standard Deviation /√n

= 4/√121

= 4/11

= 0.3636363636

n > 30, hence, The shape of the sampling distribution means is normal

Describe the pattern as n increases

As the number of random samples(n) increases the value for the standard error decreases