Question

2. TRUE or FALSE? (9 pts)

             At least 99% of all the scores are within 3 standard deviations of the mean.

       Hypothesis testing procedure uses sample statistics (based on the sample) to reach a conclusion          about the population parameter.

             It is possible to prove that the means of five populations are equal.

              The mean of all sample standard deviations is equal to the overall standard deviation.

   

             The mean of all sample means is equal to the overall mean.

           The mean is the score at the 50th percentile.

             Using statistics, it is possible to prove that smoking causes lung cancer.

       Mean of normal distribution lies at the tail of the normal curve, which is also the median and mode          of the distribution.

             Two samples are independent if the chi-squared test statistic is above 1.0.

Answer 1

(1)

At least 99% of all the scores are within 3 standard deviations of the mean.

TRUE

Explanation:

By empirical rule ofnormal probability 99.7% of the data lies within 3 standard deviation of the mean.

(2)

Hypothesis testing procedure uses sample statistics (based on the sample) to reach a conclusion          about the population parameter.

TRUE

(3)

It is possible to prove that the means of five populations are equal.

TRUE

Explaation:
By one way ANOVA:

H0:Null Hypothesis: (the means of five populations are equal.)

(4)

The mean of all sample standard deviations is equal to the overall standard deviation.

FALSE

(5)

The mean of all sample means is equal to the overall mean.

TRUE

Explntion:
By Central Limit Theorem, the mean of all sample means is equal to the overall mean.

(6)

The mean is the score at the 50th percentile.

FALSE

Explanation:
The median is the score at the 50th percentile.

(7)

Using statistics, it is possible to prove that smoking causes lung cancer.

FALSE

Explanation:

Using statistics, it isonly possible that there isa strong positive correlation between smoking and lung cancer. Correlation does not implt correlation.

(8)

Mean of normal distribution lies at the tail of the normal curve, which is also the median and mode          of the distribution.

FALSE

Explanation:
In normal distribution,mean, median and mode coincide at the mid value.

(9)

Two samples are independent if the chi-squared test statistic is above 1.0.

FALSE