Sampling And Sampling Distributions

Question 1

What is bias in statistics?

Answer 1

The tendency of a sample statistic to systematically overestimate or underestimate a population parameter.

Question 2

What is the common cause for bias in a sample?

Answer 2

Samples that are not being reflective of the population

Question 3

What is selection bias?

Answer 3

When certain groups in the population are over represented in the sample. For example if a car manufacturer only asks for advise in vintage car dealerships and gets all kinds of niche ideas

Question 4

What is nonresponse bias?

Answer 4

A systematic difference between those who are likely to respond, and those who are unlikely to respond

Question 5

What is social desirability bias?

Answer 5

When there is a systematic difference between the socially acceptable choice, and the ultimate choice that the population actually choose

Question 6

What is stratified random sampling?

Answer 6

When the population first is divided into mutually exclusive and exhaustive groups called strata that are proportionally repersented in the sample.

Question 7

What is cluster sampling

Answer 7

When the population is divided into groups and than some groups are randomly selected to be included in a sample. For example if researching grades you could say a school is a group that could be used as a same of schools in general.

Question 8

When should stratified random sampling be used vs cluster sampling

Answer 8

Stratified is better for accuracy while cluster is cheaper

Question 9

What is the difference between a parameter and a statistic?

Answer 9

A parameter is a constant that is unknown while a statistic is a random variable whose value depends on the sample choosen

Question 10

What are some other words for the sample mean

Answer 10

The estimator or the point estimator, a particular value of the estimator is called an estimate

Question 11

When is a sample mean an unbiased estimator

Answer 11

When its expected average equals that of the population mean

Question 12

What is the standard error of the sample mean

Answer 12

The standard deviation if the sample which equals the population standard deviation divided by the square root of the sample size for some reason

Question 13

Does a sample inherit normal distribution from the population?

Answer 13

Yes

Question 14

What is the central limit theorem

Answer 14

That any sample that numbers over 30 observations approaches normal distribution among the sample means even if the underlying population is not normally distributed

Question 15

Is the sample proportion an unbiased estimator of the population proportion

Answer 15

Yes

Question 16

Does the central limit theorem also apply to proportion

Answer 16

Yes, if np is larger than 5

Question 17

When should you use a finite population correction factor

Answer 17

When the sample is at least 5% of the population the sample means variance from the population mean must be reduced

Question 18

If the correction factor is close to one when adjusting the sample mean variance from the population what foes that mean

Answer 18

That the sample is close to the size of the population

Question 19

Is a finite population correction factor also applicable for the proportions of outcomes

Answer 19

Yes

Question 20

What is the statistical quality control

Answer 20

Statistical techniques used to develop and maintain a firms ability to produce high-quality goods and services

Question 21

What is acceptance sampling in statistical quality control.

Answer 21

To gather a sample of finished products and inspect them for defects

Question 22

What is the detection approach to statistical quality control.

Answer 22

To inspect the production process to find out where faults are caused

Question 23

What is chance variation in statistical quality control

Answer 23

When variation occurs randomly in the production process out of the control of employee and machine

Question 24

What is assignable variation in statistical quality control

Answer 24

Variations that are caused by events that can be identified and eliminated

Question 25

What are the characteristics of a statistical control chart?

Answer 25

It measures a stat in relation to the center line which is its expected value and it also includes an upper and lower control limit normally three standard deviations from the center line

Question 26

When is the production procedure out of control when using a control chart

Answer 26

When the expected value is outside the control limits indicating that things need to be adjusted

Question 27

What is a sign of the sample estimates veering out of control in a control chart

Answer 27

When they are not randomly spread around the center line but trends towards the upper or lower limit

Question 28

When is an estimator considered efficient

Answer 28

When it does not vary so much between samples

Question 29

What does the property of consistency mean in the context of estimators

Answer 29

That the variance of the sample mean decrease with the size of the sample as it follows the law of large numbers in probability