Q1 Variation within a set indicates a higher ____ while a set with all identical members has very low or zero ____

A1 entropy

Q2 In a decision tree we want entropy to ____ as we keep splitting

A2 decrease

Q3 When a decision tree is reversed, the increase in entropy as groups are combined is called ____

A3 information gain

Q4 When modelling data sets are split into three sets: ____

A4 the training set, the validation set, the test set

Q5 If our model does poorly on the test set, why can’t we adjust it?

A5 That would be overfitting to the test set

Q6 What do we do if a model performs poorly on a test set?

A6 Start over creating a new training, cross validation and test set

Q7

a_{11}x_{1} + a_{12}x_{2}…+a_{1n}x_{n} = b_{1}

a_{21}x_{1} + a_{22}x_{2}…+a_{2n}x_{n} = b_{2}

… … … …

a_{m1}x_{1} + a_{m2}x_{2} + … a_{nn}x_{n} = b_{n}

x_{1}, x_{2}, …, + x_{n} are the ____

A7 unknowns

Q8 a_{11}, a_{12}, … a_{mn} are the ____

A8 coefficients

Q9 b_{1},b_{2}, …b_{m} are the ____

A9 constants

Q10 In a linear system each unknown is a weight for a column vector in a ___

A10 linear combination

Q11 In a linear system each unknown is a weight for a ___ in a linear combination

A11 column vector

Q12 In a linear system each ___ is a weight for a column vector in a linear combination

A12 unknown

Q13 In a linear system, the collection of all possible linear combinations of vectors on the left-hand side is called their ____ and the equations have a solution just when the right hand vector is with that ___ . If every vector with that span has exactly one expression as a linear combination of the given left hand vectors, then any solution is unique.

A13 span

Q14 In a linear system, the collection of all possible linear combinations of vectors on the left-hand side is called their span and the equations have a solution just when the right hand vector is with that span . If every vector with that span has exactly one expression as a linear combination of the given left hand vectors, then any solution is ____.

A14 unique

Q15 In a linear system, the collection of all possible linear combinations of vectors on the left-hand side is called their span and the equations have a solution just when the right hand vector is with that span. If every vector with that span has exactly ____ as a linear combination of the given left hand vectors, then any solution is unique.

A15 one expression

Q16 The number of vectors in a basis (its dimension) cannot be ____ than m or n but it can be smaller

A16 larger

Q17 If we have m independent vectors, a solution is ____ regardless of the right hand side, otherwise not

A17 guaranteed

Q18 In an underdetermined system, the dimension of the solution set it usually equal to ___

A18 n – m where n is the number of variables and m is the number of equations

Q19 When a linear system is inconsistent it is possible to derive a ___ from the equations that may always be rewritten as 0 = 1

A19 contradiction

Q20 When a linear system is inconsistent it is possible to derive a contradiction from the equations that may always be rewritten as ____

A20 0 = 1

Q21 A system of equations whose left hand sides are linearly independent is always ___

A21 consistent

Q22 A system of equations whose left hand sides are ____ is always consistent

A22 linearly independent

Q23 A system of equations whose left-hand sides are linearly independent is always consistent.

A23 left-hand sides

Q24 an explicit formula for the solution of a system of linear equations with each variable given by a quotient of two determinants

A24 Cramer’s Rule

Q25 Cramer’s Rule is an explicit formula for the solution of a system of linear equations with each variable given by a quotient of two

A25 determinants

Q26 an explicit formula for the solution of a system of linear equations with each variable given by a of two determinants

A26 quotient

Q27 ndarray.dtype – what’s this show? (NumPy)

A27 the data type each element of the array is comprised of

Q28 b = array ([(1.5,2,3), (4,5,6,)])

A28 two

Q29 The type of the array can also be explicitly specified ____

A29 at creation time

Q30 Often the elements of an array are originally unknown but its size is known. Hence NumPy offers several functions to create arrays with initial ____ content

A30 placeholder

Q31 The function zeros creates ____? (NumPy)

A31 an array full of zeroes

Q32 The function ____ creates an array whose initial content is random and depends on the state of memory

A32 empty

Q33 Gauss completed Disquisitiones Arithmeticae, his magnus opus, in 1798 at the age of 21. This work was fundamental in consolidating ____ as a discipline

A33 number theory

Q34 If you start typing in the console or editor and hit the ___ key, Rstudio will suggest functions or file names

A34 tab

Q35 Start typing in the Rstudio interactive console (not the code editor window) and hit ____ to show a list of every command you’ve typed starting with those keys

A35 ctrl + up

Q36 Press ____ in Rstudio to execute the current line of code

A36 ctrl + enter

Q37 Set the working directory R

A37 setwd() – dir path in (), replace \ with /

Q38 command for installing R package

A38 install.packages(“thepackagename”)

Q39 See installed R packages

A39 installed.packages()

Q40 to use an R package in your work once it’s installed, load it with ____

A40 library(“thepackagenmame”)

Q41 Update R packages

A41 update.packages()

Q42 help with a function in R

A42 ?functionName

Q43 Show an example of a function in use (R)

A43 example(functionname)

Q44 Display a list of function’s arguments

A44 args(functionName)

Q45 Search R help for a term

A45 ?? (“term”)

Q46 assignment in R can be done using the function ___

A46 assign() eg. assign(“x”, c(10.4,5.6))

Q47 What’s wrong with this (R)

c(10.4,5.6) -> x

A47 nothing

Q48 Vectors can be used in arithmetic expressions in which case operations are performed ____

A48 element by element

Q49 If vectors in the same expression are not the same length, the value of the expression is ?

A49 A vector with the same length as the longest vector which occurs in the expression

Q50 y has 11 elements, x has 5 elements

v <- 2*x + y + 1 generates a new vector of length ___ (R)

A50 11

Q51

y has 11 elements, x has 5 elements

v <- 2*x + y + 1 generates a new vector of length 11

is constructed by adding 2*x ___ times

A51 2.2

Q52

y has 11 elements, x has 5 elements

v <- 2*x + y + 1 generates a new vector of length 11

constructed by repeating y ___ times

A52 1

Q53 y has 11 elements, x has 5 elements

v <- 2*x + y + 1 generates a new vector of length 11

constructed of 1 repeated __ times

A53 11

Q54 sort(x) – returns what? (R)

A54 a vector of the same size as x with the elements arranged in increasing order

Q55 1:30 creates ? (R)

A55 c(1,2,…,29,30)

Q56 30:1 creates ? (R)

A56 c(30,29,…,2,1)

Q57 A vector can be used by R as an array only if it has a dimension vector as its ___ attribute

A57 dim

Q58 if the dimension vector for an array a is c(3,4,2) then there are ___ entries in a? (R)

A58 3*4*2 = 24