ECONOMETRICS INTRO (L0&L1)

Question 1

Descriptive statistics

Answer 1

Using mean,variance and correlation etc to help us understand the affect of variables

Question 2

Forecasting

Answer 2

Predicting future outcomes eg interest rates

Question 3

Estimating

Answer 3

How much one variable will affect another

Question 4

Big data

Answer 4

How we analyse huge/complex data sets

Question 5

Properties of big data

Answer 5

Volume
Variety
Velocity
Veracity

Question 6

Volume

Answer 6

Large no of observations/variables

Question 7

Variety

Answer 7

Different forms data comes in (video,text)

Question 8

Velocity

Answer 8

How quick data can be recorded eg facebook posting

Question 9

Veracity

Answer 9

The quality of the data

Question 10

(A+B)’ (transposed)

Answer 10

A’+B’

Question 11

(A’)’ (transposed)

Answer 11

A

Question 12

(KA)’ (transposed)

Answer 12

KA’

Question 13

(AB)’ (transposed)

Answer 13

B’A’

Question 14

Square matrix

Answer 14

Rows=columns, can’t find the inverse for any other type

Question 15

Symmetric matrix

Answer 15

Transposed=not transposed A’=A

Question 16

Inverse matrix

Answer 16

A x A’ = I
BA=AB=I
If the matrix has an inverse it’s invertible/non-singular

Question 17

(A-1)-1

Answer 17

A

Question 18

(A’)-1

Answer 18

(A-1)’

Question 19

(AB)-1

Answer 19

B-1A-1

Question 20

(BA)-1

Answer 20

A-1B-1

Question 21

((AB-1))’

Answer 21

(AB’)-1=(B’A’)-1=(A’)-1(B’)-1

Question 22

|A’|

Answer 22

|A|

Question 23

|AB|

Answer 23

|A|B|

Question 24

|KA|

Answer 24

K^n |A|
Where n is the number of rows/columns

Question 25

Collinearity

Answer 25

The rows and columns are the same so the determinant is 0
(12
12)

Question 26

A is invertible when…

Answer 26

The determinant does not equal 0, also means the rank= number of rows

Question 27

Orthogonal

Answer 27

Xi’xj=0

Question 28

Rank(AB)

Answer 28

If the rank isn’t equal of matrix A or B, then use the lower rank

Question 29

Tr(A’)

Answer 29

Tr(A)

Question 30

Tr(A+B)

Answer 30

tr(A)+tr(B)

Question 31

Tr(AB)

Answer 31

Tr(BA) if they’re square matrices (cyclicity of trace)

Question 32

Tr(KA)

Answer 32

Ktr(A)

Question 33

A is positive definite if

Answer 33

The quadratic is >0

Question 34

A is positive semidefinite if

Answer 34

The quadratic is >_0

Question 35

A is negative definite if

Answer 35

The quadratic is <0

Question 36

A is negative semidefinite if

Answer 36

The quadratic is <_0

Question 37

Symmetric matrix properties

Answer 37

Positive definite, non singular
Semidefinite if det(A) and tr(A) are positive If A has a positive determinate, then A^k will also be positive

Question 38

Idempotent

Answer 38

A^2=A eg Identity matrix