statistics quiz

1 The law of large numbers affects sampling procedure how?

     a  Large numbers indicate relatively large sampling errors.

     b  Large samples create distributions with small mean values.

     c  Large samples tend to minimize sampling error.

     d  Large numbers eliminate sampling error.

2 A z-score of 2.0 is two standard deviations above the mean of the distribution (t).

       True

       False

3 In a distribution for which the mean is 25 and the standard deviation is 5, what percentage of all scores occur between 20 and 30?

     a  34.13%

     b  68.26%

     c  84.13%

     d  92.39%

4 How is the z-test different from z-score analysis?

     A The z-test compares a sample to a population.

      b The z-test calculates a value of z which can be compared to Table A.

      c The z-test provides a way to evaluate how individuals compare to a population.

      d The z-test is based on how individual scores compare to a sample mean

5 What is the critical value of t for a two-tailed t-test in which n = 10?

     a  2.262

    b   2.228

   c    .05

    d   .01

6 In the z transformation formula, z = (x – M)/s the x stands for __________.

  a     an unknown value

 b      the mean of the z distribution

 c      the standard deviation of the distribution

d       the value to be transformed into z

7 Rejecting the null hypothesis is the same as saying _____________.

a       any differences are random differences

 b      the result is statistically significant

c       the hypothesis of difference is rejected

  d     the research hypothesis is rejected

8 The z-score transformation makes non-normal scores normal.

       True

       False

9 The z scores is a ratio of difference to variability (t)

       True

       False

10 Question 10 of 10 A z-score of 0 occurs at a point beyond 75% of all scores (f).

       True

       False