my flashcards

Question 1

question we ask ourselves to determine if a variable is quantitative or categorical in Stats 1. chapter 1

Answer 1

does our variable tell us the quantitiy of something measured

Question 2

question we ask ourselves to determine if a categorical variable is ordinal or nominal

Answer 2

does the variable tells us anything about the order of the variable?

Question 3

On a transactions table, what type of variable is the date? categorical or Quantitative? what are their units?

Answer 3

quantitative and units are days. although its weird because its also ordinal. its a bit relative

Question 4

An economist assesses the probability of the interest rate increasing in a certain situation to be 0.6

what type of probability is this and why

Answer 4

The probability is​ subjective, because the probability represents a personal degree of belief.

Question 5

what formula should you use for this question regarding the probabiltiy of this: out of 2 students, The probability that one or the other will be marketing majors (not independent)

Answer 5

​P(A or ​B)=​P(A)+​P(B)−​P(A and​ B)

Question 6

What is Cross-Section Data? - types of data STATS

Answer 6

Answer: Observations collected at a single point in time.

Focus: Differences between individuals, groups, or entities.

Example: Survey of 1,000 households’ income levels in 2025.

Question 7

What is Time Series Data?

Answer 7

Answer: Observations collected over time for a single entity or variable.

Focus: Changes and trends over time.

Example: Monthly unemployment rates in Canada from 2010 to 2025.

Question 8

What is the conditional probability for independent events

Answer 8

P(A | B) = P(A)

P(B | A) = P(B)

Question 9

what does this mean on excel? =FACT(N)

Answer 9

It returns the factorial of N. In other words, n!

Question 10

what does this mean on excel? =COMBIN(N,K)

Answer 10

It returns the number of ways to choose K items from N without repetition and without order. Mathematically, it calculates ……. .N! / K!(n-K)!

Question 11

what does this mean on excel? =BINOM.DIST(k, N, P, FALSE)

Answer 11

For Exact Successes (PMF)
P(X = k) =𝑃(𝑋 = 𝑘) = ( 𝑛!/ (𝑘!∗(𝑛−𝑘)!)) ∗ 𝑝^(𝑘) ∗ 𝑞^(𝑛−𝑘)

Question 12

2 types of Random variables

Answer 12

Discrete and Continuous

Question 13

Description of random variable type discrete

Answer 13

can only take speciric values (countable) (integer)

Question 14

Description of random variable type continuous

Answer 14

Can take any value in an interval (infinite possibilities) (decimal, infinite)

Question 15

Adding/Subtracting a Constant (C)

what acc happens? definition of adding or substracting C

Answer 15

If we add/subtract a fixed number (C) to a random variable (X), it shifts the values but does not change the spread. * SD and variance stay the same, EX moves up or down

Question 16

what are the 3 discrete probability models distributions

Answer 16

Geometric, binomial, poisson

Question 17

formula to calculate coefficient of variation. the higher the coefficient the higher the risk (in the context of investment)

Answer 17

Coefficient of variation = SD/E[x]

Question 18

Why does the Z-table give the probability of “less than” a given z-score?

Answer 18

The Z-table always measures from the far left up to the given z-score (cumulative probability).
* P(Z \leq z) gives the area to the left of z .
* To find P(Z > z) , use the complement: 1 - P(Z \leq z) .
* Think of it like a ranking: the table tells you what percentage of values are below a certain point.

Question 19

Distribution Rule which needs to be whole numbers?

Answer 19

in the discrete models, n (number of trials) must be a whole number because it represents the number of attempts.

Question 20

variance normal formula

Answer 20

(x-Ex)^2 * p

Question 21

variance geometric model

Answer 21

q/p^2

Question 22

variance binomial model

Answer 22

npq

Question 23

variance poisson

Answer 23

= EX = lambda

Question 24

variance uniform distribution

Answer 24

(b-a)^2 ] / 12

Question 25

variance normal distribution

Answer 25

= Ex (x-Ex)^2

Question 26

Expected value or mean normal formula

Answer 26

sum of x*p

Question 27

expected value or mean geometric

Answer 27

1/p

Question 28

expected value or mean binomial

Answer 28

n*p

Question 29

expected value or mean poisson

Answer 29

= Varx=lamnda

Question 30

Expected value or mean uniform distribution

Answer 30

(a + b) / 2

Question 31

expected value or mean normal distribution

Answer 31

center of curve. always given

Question 32

geometric model formula

Answer 32

q^k-1 *p

Question 33

What model do we use for this question? How many trials until the first success?

Answer 33

Geometric Distribution

Question 34

What model do we use for this question? How many successes occur in a fixed number of trials?

Answer 34

Binomial Distribution

Question 35

What model do we use for this question? How many rare events happen in a fixed time or space?

Answer 35

Poisson Distribution

Question 36

What model do we use for this question? What distribution describes averages or large samples?

Answer 36

Normal Distribution

Question 37

Geometric Distribution → What question do we ask to determine this?

Answer 37

Looking for the first success in repeated trials?

Question 38

Binomial Distribution → What question do we ask to determine this?

Answer 38

Counting successes in a fixed number of trials?

Question 39

Poisson Distribution → What question do we ask to determine this?

Answer 39

Counting rare events over a fixed time/space?

Question 40

When Poisson's λ is large (more than 10), and it's easier to approximate with which continuous distribution?

Answer 40

Use Normal distribution when Poisson's λ is large (typically λ > 10) for easier calculations.