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EPI Statistical Methods > 1.1 Terminology > Flashcards

1.1 Terminology Flashcards

1
Q

Does a sample mean the same thing in statistics and biology?

A

No, for example, sample and population are not the same in statistics and in biology

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2
Q

What is an individual observation?

A

Value (numerical or not) taken by a variable observed on an individual

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3
Q

What is the smallest unit in data collection? What are other units?

A
  • Individual (smallest)
  • Group
  • Population (largest)
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4
Q

What is a statistical sample of size n? What is it also called?

A
  • n individual observations
  • Also called “sample data”
  • n values taken by a variable observed on n individuals
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5
Q

For a given variable, how many individual observations would be observed for 1 individual?

A

1 individual observation

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6
Q

For a given variable, how many individual observations would be observed for a group of n individuals? What is this called?

A

n individual observations (statistical sample)

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7
Q

For a given variable, how many individual observations would be observed for a population of N individuals? What is this called?

A

N individual observations (statistical population)

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8
Q

What is the difference between n and N?

A
  • N>= n
  • n (statistical sample)
  • N (statistical population)
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9
Q

What are the two main types of random variables?

A
  • Qualitative (characters)

- Quantitative (numbers: integers, fractions, or real numbers)

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10
Q

What is the nominal scale?

A
  • All one can do with the observations is “name” them

- Ex: symbols (+, -, $)

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11
Q

What is the ordinal scale?

A
  • There is an order to allow for observations to be ranked: alphabetical or numerical
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12
Q

What is the interval scale?

A
  • In the absence of a true zero point, data can be positive or negative
  • Or, are strictly positive, so that ratios make sense
  • Ex: temperatures in celsius, IQ
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13
Q

What is a ratio scale?

A
  • There is a true zero point and ratios do make sense

- Ex: temperatures in Kelvin

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14
Q

“Plant vigor, from weak to strong” is an example of what kind of scale?

A

Ordinal

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15
Q

“Temperature in celsius” is an example of what kind of scale?

A

Interval

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16
Q

”+, -, $, ?” is an example of what kind of scale?

A

Nominal

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17
Q

“Temperature in Kelvin” is an example of what kind of scale?

A

Ratio

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18
Q

What is a random variable?

A

Associated with the uncertainty of the outcome of an observation

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19
Q

List the scales of observation from the scale that you can manipulate the least to the most.

A
  • Nominal (least)
  • Ordinal
  • Interval
  • Ratio (most)
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20
Q

What are three orders used by the ordinal scale?

A
  • Alphabetical (A is smaller than B)
  • Numerical
  • Grades (A is greater than B)
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21
Q

“Numerical codes, such as 032, 134, etc.” are an example of which kind of scale?

A

Ordinal scale

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22
Q

Which scales of observation are qualitative? Which scales are quantitative?

A
  • Qualitative: nominal and ordinal

- Quantitative: interval and ratio

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23
Q

Define an individual.

A

Location observed on a given day at a given time

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24
Q

Can the length of an interval be negative?

A

No, it must always be positive

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25
Statistically speaking, the number of towns visited by a candidate on a day during an election campaign (Note: Candidates may take ‘days off’, when they visit no town.) is observed at the _________ scale.
ratio
26
Statistically speaking, the number of towns visited by a candidate on a day during an election campaign represents what kind of data?
Discrete quantitative
27
Statistically speaking, the budget of a government in a given year (defined as the sum of predicted incomes and outcomes, rounded to the nearest million of the national currency) is observed at the _________ scale.
interval
28
Statistically speaking, the budget of a government in a given year (defined as the sum of predicted incomes and outcomes, rounded to the nearest million of the national currency) represents what kind of data?
Discrete quantitative
29
True or False: The sample mean is random because its value changes from random sample to random sample.
True
30
True or False: The variance of a random sample made of negative numbers is zero or positive.
True
31
True or False: The expected value of the sum of two random variables is always equal to the sum of the population means of the two random variables.
True
32
True or False: In the general case, the population variance of the sum of two random variables is equal to the sum of the population variances of the two random variables plus an extra term.
True
33
True or False: The "3M statistics" are not all equal when the sample distribution is symmetrical and bimodal.
True
34
True or False: A sample variance is negative.
False
35
True or False: The sample mean and the sample standard deviation are expressed in the same unit.
True
36
True or False: The "3M statistics" are not all equal when the sample distribution is skewed.
True
37
True or False: By definition, the coefficient of variation is a percentage.
True
38
The magnitude of an earthquake, rounded to the first decimal, is observed (statistically speaking) at the _____ scale.
interval
39
The magnitude of an earthquake, rounded to the first decimal is what type of variable?
Discrete quantitative
40
When traveling around the world, there usually is a time delay between the clock times in the departure city and once at destination, called “jet lag”, which is a number of hours: 0, 1, 2, 3, ... 14 between Montréal and Tokyo. The jet lag, depending on the travel/traveler, is observed (statistically speaking) at the _________ scale.
ratio
41
Jet lag, a number of hours, is what type of variable?
Discrete quantitative
42
True or False: The variance of a sample made of constant quantities (e.g., n = 3 and x1 = x2 = x3 = 10) is zero.
True
43
True or False: By definition, the sample mean | is non-negative.
False
44
The destination (city, country) of a holiday trip is an example of what kind of data?
Qualitative
45
The difference between the number of passengers on a “go flight” from destination A to destination B in a given evening and the number of passengers on the “return flight” from destination B to destination A in the following morning is an example of what kind of variable? The random variable is observed at the _________ scale.
Discrete quantitative | interval
46
True or False: The median may exist for a sample of qualitative data.
True
47
True or False: The population mean of a normal distribution is also its population median and population mode
True
48
True or False: The sample mean and the sample variance are expressed in the same unit.
False
49
True or False: The population variance is zero.
True
50
The exact distance (without rounding to the nearest km) between the departure point and the arrival point is an example of what variable?
Continuous quantitative
51
The consumption of meat per Canadian resident (expressed in kg, without any rounding) is an example of what variable?
Continuous quantitiative
52
The distribution of the world human population per continent (expressed as a percentage, rounded to the nearest percent) is an example of what variable?
Discrete quantitative
53
The diet regime of an animal (e.g. herbivorous, carnivorous, omnivorous) is an example of what variable?
Qualitative
54
The date on which a mine accident occurs in the world is an example of a random variable observed at which scale of observation?
Ordinal scale
55
In a survey made by a company, the level of satisfaction of an employee at work, expressed as "highly satisfied", "moderately satisfied", "moderately unsatisfied", and "excessively unsatisfied" is an example of which variable? Which scale of observation does it utilize?
- Qualitative | - Ordinal scale
56
The budget of a company, expressed as the difference between incomes and outcomes in a given year, is an example of which variable? Which scale of observation does it utilize?
- Discrete quantitative | - Interval scale
57
The number of people who hold a valid car driving license in a family is an example of which variable?
Discrete quantitative
58
The balance of the budget of a government (i.e. incomes minus expenses) can be seen as a random variable observed (statistically) at which scale of observation?
Interval scale
59
The colour of a leaf on a maple at the end of October (i.e. from yellow to brown, with green, orange and red in-between) is an example of which variable? Which scale of observation does it utilize?
- Qualitative | - Ordinal
60
True or False: The "3M statistics" are all equal, while the sample distribution is symmetrical and has one mode.
True
61
True or False: The "3M statistics" are all equal, while the sample distribution is symmetrical and has two modes.
False
62
True or False: The sample mean and the sample variance are expressed in different units.
True
63
True or False: The population variance is negative.
False

EPI Statistical Methods (12 decks)

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