Statistics

Question 1

Formula for finding the mean of a population

Answer 1

μ = ΣX / n

Question 2

Formula for finding the mean of a sample

Answer 2

Mean (X bar) = ΣX / n

Question 3

Formula for finding the spread of a population

Answer 3

Var = Σ(X-Xbar)^2
————-
n

Question 4

Formula for finding the spread of a sample

Answer 4

Sd =

ROOT: Σ(X-Xbar)^2
————-
n-1

Question 5

GROUPED DATA: estimating median (Q2) using linear interpolation.

170    Q2.            175
  I         I.                 I 
  ------------------
  I.        I.                 I 
13.      14.5.           20

What is the formula for finding Q2?

Answer 5

Q2-170 = 14.5-13
——– ———
175-170 20-13

Question 6

Notation for a mean in terms of X

Answer 6

X with a line across the top (X bar)

Question 7

Define an outlier.

Answer 7

Any data point more than 1.5 x the IQR below Q1 or above Q3.

Question 8

What is Q1?

Answer 8

The lower quartile, LQ

Question 9

What is Q2?

Answer 9

The median

Question 10

What is Q3?

Answer 10

The upper quartile, UQ

Question 11

Why do we use coding?

Answer 11

To make the numbers easier to work with.

Question 12

If the graph is leaning towards the right (has a left tail), the skew is:

Answer 12

Negative skew

Question 13

If the graph is leaning towards the left, and has a right tail, the skew is:

Answer 13

Positive skew

Question 14

If the graph is symmetrical, the skew is:

Answer 14

Undefined

Question 15

Median =

Answer 15

n+1
—- th value
2.

Question 16

What do you have to do before calculating medians and IQR?

Answer 16

Sort the data in ascending order

Question 17

IQR =

Answer 17

UQ - LQ

OR

Q3 - Q1

Question 18

MSD (mean square deviation) =

Answer 18

     n

Question 19

RMSD ( root mean square deviation) =

Answer 19

Root (MSD)

Question 20

(Sample) SD (standard deviation) =

Answer 20

ROOT: Σ(Χ-Χbar)^2
————-
n-1

Question 21

What’s the quicker formula for MSD?

Answer 21

         n

Question 22

What does E(y) mean?

Answer 22

“Mean of y”

Question 23

What is the coding version of y = mx + c?

Answer 23

y = ax + b , where a and b are constant

Question 24

E(y) =

Answer 24

a x E(X) + b

Question 25

sd(y) =

Answer 25

a x sd(X)

Question 26

Var(y) =

Answer 26

a^2 x Var(X)