Statistics

PART A
A researcher is conducting an experiment to evaluate a treatment that is expected to increase the scores for individuals in a population which is known to have a mean of μ = 80. The results will be examined using a one-tailed hypothesis test. Which of the following is the correct statement of the null hypothesis? 

• μ > 80
• μ > 80
• μ < 80
• μ < 80

Which of the following will increase the power of a statistical test? 

• change α from .05 to .01
• change from a one-tailed test to a two-tailed test
• change the sample size from n = 100 to n = 25
• None of the other options will increase power. 

Which of the following samples would have the smallest standard error? 

• n = 25 scores from a population with σ = 10
• n = 25 scores from a population with σ = 20
• n = 100 scores from a population with σ = 10
• n = 100 scores from a population with σ = 20

. Which answer incorrectly describe the graph?

• Both distributions have equal mean
• Both distributions have equal mode
• Both distributions have equal median
•  Both distributions have equal standard deviation

Which of the following is not a continuous variable?

• weight
• speed of a moving car
• Type of computers
• Age of teachers

Rearrange the steps of hypothesis testing below
I.  Make a decision
II.  State the hypotheses
III.  Select the alpha level
IV.  Locate the critical region
V.  Compute the test statistic

• a)  I, II, III, IV, V
• a)  II, IV, I, III, V
• a)  II, III, IV, V, I
• a)  III, V, IV, II, I

Below are properties of the standard deviation, except

• a)  The sum up of deviation scores in a distribution will be zero.
• a)  If the mean changes and each data changed constantly, the standard deviation will have a new value.
• a)  If a constant is added to every score in a distribution, the standard deviation will not be changed.
• a)  If each score in a distribution is multiplied by a constant, the standard deviation will be multiplied by the same constant.

Factors that affect variability are
I.  Infinite scores
II.  Manipulating sample size
III.  Single or multiple extreme values
IV.  The range that changes unpredictably from sample to sample

• a)  I and II
• a)  III and IV
• a)  I, II and III
• a)  All of the above

The stem and leaf plot below shows the number of books bought by students in one book festival. Which of the following statements are true?        
I. The range is 59.
 II. The median is 38.5.
III. The mean is 37.

• I only 
• II only 
• III only 
• I and II 

Which of the following statements are true?  
 I. Mode identifies the location of the peak in the frequency distribution graph
II. There can be more than one mode but no mode is impossible
III. Changing value of any score will change the mean
 IV. The symbol of median is ∑

• I and II
• II and IV
• I and III 
• III and IV