Quiz

Question 1

What is an observation?

Answer 1

An observation is an individual occurrence or instance that we are interested in

Question 2

What is a variable?

Answer 2

A variable is a characteristic or outcome that can vary from observation to observation

Question 3

What is data?

Answer 3

Data is a collection of recorded information on one or more variables for a set of observations

Question 4

What are the general types of variables? Define.

Answer 4

Qualitative (categorical) variables) are those that classify observations into one of a group of categories. Think “quality” or “what type”

Quantitative (numerical) variables are those that can be measured on a naturally numerical scale. Think “quantity” or “how much”

Question 5

What are the types of quantitative variables?

Answer 5

Steps vs ramp

Discrete variables take on a countable number of values in a given range. You could list or count all the possible values or outcomes for a variable (steps)

A continuous variable is a variable that can take on an infinite number of values ina given range, thus every value within range i a possible value.
Think ramp

Question 6

What are the levels of measurement?

Answer 6

NOIR
Nominal
Ordinal
Interval
Ratio

Question 7

What is a nominal scale?

Answer 7

One that classifies observations into one of a group of mutually expansive categories that cannot be meaningfully ranked or ordered

Ie: religions: Jewish, muslin, Christian

Question 8

What is an ordinal scale?

Answer 8

One that classifies observations into one of a group of mutually exclusive categories that have meaningful rank or order

Finishing first or second in a race
Mood/ pain scales

Question 9

What is interval scale?

Answer 9

Like ordinal scale, but the difference between any two values is the same. Interval scales have no “mathematically meaningful” zero/ the most you can do with an interval scale is measure the difference between who observations

Ex. Celsius, IQ scores

Question 10

What is the ratio scale?

Answer 10

The same as interval scale except that there is a “mathematically meaningful” zero. That is, when you have 0 on a ratio-scaled variable, it means that there is none of the variable

Ex. Number of children, weight

Question 11

What is a population?

Answer 11

A set of all observations we are interested in when we study the behaviour of a variable

Pop size = N

Question 12

What is a sample?

Answer 12

A select subset of observations from teh population, usually much smaller than the population itself
‘
Denoted n

Question 13

What are the different sampling techniques?

Answer 13

Random sampling:
- Simple random sample (SRS)
- Stratified sampling
- Cluster sampling
- Systematic sampling

Non-random sampling:
- convienice sampling
- voluntary sampling

Question 14

What is simple random sampling?

Answer 14

Random sampling
Every conceivable subgroup of n observations has the same chance as being selected for the sample size of n. A random number generated is required.

Question 15

What is stratified sampling?

Answer 15

Random sampling
Done when the population of interest contains naturally occurring groups (or strata) of observations that are similar on one or more characteristics. Obtained by selecting observations from each strata and combining them in a sample

Question 16

What is cluster sampling?

Answer 16

Random sampling
Done when the population of interest contains naturally occurring clusters that do not greatly differ from cluster to cluster but contain observations with differing characteristics. Obtained by selecting one of these clusters as the sample.

Question 17

What is systematic sampling?

Answer 17

(1-n-k sampling)
Random
Is done when every kth observation is selected from a list of N observations in a population. A systematic sample comprises every kth selected observation

Question 18

What is convenience sampling?

Answer 18

Non-random
When the observations selected for the sample are simply those that are easiest to reach

Question 19

What is voluntary sampling?

Answer 19

Non-random
Done when the observations (people) “volunteer” to be in the sample

Question 20

What are the types of sampling bias?

Answer 20

Sampling (or selection) bias
Non response bias
Measurement bias

Question 21

What is sampling bias?

Answer 21

Occurs when a subset of the population has a lower or higher chance of being selected for a sample compared to the rest of the population

Question 22

What is non-response bias?

Answer 22

Occurs when a response is not recorded (for whatever reason) form some portion of the sample

Question 23

What is measurement bias?

Answer 23

Occurs when a false/incorrect/untrue response is obtained from a portion of the sample

Question 24

What is a controlled experiment?

Answer 24

Establishes a cause and effect relationship between an explanatory (independent) variable and a supposed response (dependant) variable
Established in a controlled setting
There is a treatment and control group

Question 25

What is an observational study?

Answer 25

“Hands off”
Researchers do not interfere with with the individuals in the sample, but simple record information on the variables of interest
Cannot be used to establish a cause and effect relationship between two variables, only some association between them

Question 26

What is a lurking variable ?

Answer 26

A variable that can affect the response variable but is not accounted for by a study’s design.

Question 27

What is an explanatory vs a response variable?

Answer 27

Explanatory (independent) - type one that is suspected to explain or cause changes in the other

Response (dependant) - the variable that is suspected to gained due to the changes in the explanatory variable

Question 28

How do you fill in a frequency table?

Answer 28

R: table()

Using the sample proportion formula p^
P = X/n
X+ number of observations in category
N = sample size

Question 29

What is a sample proportion? How do you find it?

Answer 29

A ratio or fraction of a sample

P = X/n
X= number of observations in a particular category
n = sample size

Question 30

How do you compute upper and lower fences?

Answer 30

Upper fence = Q3 +1.5 (IQR)
Lower fence = Q1– 1.5(IQR)

Question 31

What are measures of central tendency? Measures of variation (spread)?

Answer 31

Measures of central tendency describe the tendency of the variables to center or cluster about certain values (mean (x^—), median(x^~)

Measures of variation describes the variation of the observation about a measure of central tendency (variance (s^2), standard deviation (s))

Question 32

What summary values are appropriate for a symmetrical distribution?

Answer 32

Central tendency = mean (x^—)

Spread: variance or standard deviation (s or s^2)

Question 33

What is the most appropriate summery of values for skewed graphs?

Answer 33

Central tendency: median (x^~)

Measure of spread: IQR