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Question 1

how do you calculate the mean of a frequency distribution

Answer 1

midpoint of each class x frequency = x
sum of all the x = y 

x/y = mean
- verify this

Question 2

The median is also the

Answer 2

50th percentile or Q2

Question 3

when calculating descriptive statistics for grouped data

Answer 3

treat data values as if they occur at the midpoint of a class (ie in frequency distribution)

Question 4

the value of the sd can never be

Answer 4

negative

Question 5

The variance can never be

Answer 5

negative

Question 6

If all the observed value sin a sample are close to the sample mean the sd will be

Answer 6

small (close to zero)

Question 7

If the observed values vary widely aroudn the sample mean, then SD will be

Answer 7

large

Question 8

If all of the vaLues in the sample are identical the sample sd will be

Answer 8

zero

Question 9

The sum of the deviations from the mean is

Answer 9

zero

Question 10

Can the variance of a sample be negative

Answer 10

no

Question 11

Correlation coefficient ranges between

Answer 11

-1 and +1

Question 12

Range is a measure of

Answer 12

variability

Question 13

IQR is a measure of

Answer 13

Variability

Question 14

Variance is a measure of

Answer 14

variability

Question 15

SD is a measure of

Answer 15

variability

Question 16

Skewness is a measure of

Answer 16

distribution of shape

Question 17

z-scores is a measure of

Answer 17

distribution of shape

Question 18

Covariance is a measure of

Answer 18

linear association b/w 2 variables

Question 19

correlation coefficient is a measure of

Answer 19

association b/w 2 variables

Question 20

Covariance is a measure of how two variables change together, but its magnitude is unbounded, so it is difficult to interpret. By dividing covariance by the product of the two standard deviations, one can calculate the normalized version of the statistic. This is the

Answer 20

correlation coefficient.

Question 21

If SXY is positive

Answer 21

there is a positive linear association b/w x and y

Question 22

if sxy is negative

Answer 22

there is a negative linear association between x and y

Question 23

what calculation would you use to dispersed distribution if you have the mean and the standard deviation

Answer 23

coefficient of variation , the higher the number, the more dispersed

Question 24

When computing the geometric mean, how is it different than computing the mean where the values are concerned

Answer 24

you multiply your values together for Geo where mean you add them

Question 25

Prob the that you get A and b? independent

Answer 25

Probability of A union B which is P(AnB) = P(A) x p(B)

Question 26

Prob of at least one

Answer 26

Prob of A or B which is P(AuB) = P(A) + P(B) for independent 
and P(A)+P(B) - P(AnB) for dependent

Question 27

do not get either A or B

Answer 27

P(B) + (PAnB)

Question 28

No A but yes to B

Answer 28

P(Ac) + P(AnB)