ICS Part 2 Statistics Chapter 12 Online Test

The following statistic are unbiased estimators:

• The Sample mean A
• S² = Σ(X - X)²/n-1 B
• The sample proportion C
• All the above D

Confidence intervals which are often used in practice are

• 90% A
• 95% B
• 98% C
• all of these D

An estimator is ------------ if its expected value is equal to the population parameter to be estimated

• bad A
• biased B
• unbiased C
• none of these D

Large sample contains more than

• 5 values A
• 10 values B
• 20 values C
• 30 values D

If (1-α) is increased, the with of a confidence interval is:

• Decreased A
• Increased B
• Constant C
• Same D

The endpoints of a confidence interval are called:

• confidence coefficient A
• Confidence limits B
• Error of estimation C
• Parameters D

Small sample has less than

• 50 values A
• 45 values B
• 30 values C
• 35 values D

If the observations are paired and the number of pairs is n, then the number of degree of freedom is equal to

• n A
• n - 1 B
• 2n C
• 2n - 1 D

A single value used to estimate a population value is called:

• Interval estimate A
• Point estimate B
• Confidence interval C
• Level of confidence D

By increasing the sample size, the precision of confidence interval is:

• Decreased A
• Increased B
• Constant C
• Unchanged D

A range of values used to estimate an unknown population parameter is

• a point estimator A
• An interval estimator B
• an unbiased estimator C
• A biased estimator D

Statistical inference has two branches namely:

• Level of confidence and degrees of freedom A
• Biased estimator and unbiased estimator B
• Point estimate and interval estimate C
• Estimation of parameter and testing of hypothesis D

The probability associated with confidence interval is called:

• Level of confidence A
• Confidence coefficient B
• Both A and B C
• Confidence limits D

Level of significance is denoted by

• 2 - α A
• 3 - α B
• α C
• 1 - α D

Estimate is the observed value of an:

• Unbiased estimator A
• Estimation B
• Estimator C
• Interval estimation D

The precision can be increased by  ---------------- the sample size

• increasing A
• decreasing B
• changing C
• ignoring D

• biased A
• unbiased B
• positively biased C
• none of these D