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Spring 2025 > Statistics > Flashcards

Statistics Flashcards

1
Q

Difference between interval and ratio

A

A ratio has a meaningful 0, but an interval does not

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2
Q

Parameter

A

A numerical characteristic of a whole population that can be estimated by a statistic

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3
Q

Statistic

A

A number that represents the property of a sample

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4
Q

Data

A

The values of a variable

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5
Q

Descriptive Statistics

A

Information directly related to gathered data

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6
Q

Inferential Statistics

A

Making predictions/generalizations based on descriptive statistics

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7
Q

Nominal Data

A

Data with no order or ranking

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8
Q

Record Surveying

A

Extracting data from existing sources

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9
Q

Simple Random Sampling

A

Sample selected using chance methods or random numbers
(E.g. drawing names from a hat)

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10
Q

Stratified Sampling

A

Population is divided into groups according to specific characteristics before random sampling begins

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11
Q

Cluster Sampling

A

Sampling using already-existing groups (e.g. households)

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12
Q

Systematic Sampling

A

First subject is selected randomly from entire population, then selecting every kth element from population

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13
Q

Convenience Sampling

A

Using subjects that are convenient
Biased

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14
Q

Sampling with replacement

A

Once a member is chosen, the member re-enters the population and can be chosen again

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15
Q

Sampling Error

A

The natural tendency of a sample to not be an exact representation of the population

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16
Q

Nonsampling Error

A

Errors in sampling not caused by the sampling process itself

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17
Q

Frequency Distribution

A

The organization of raw distribution data in a table

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18
Q

Hawthorne Effect

A

The tendency of experiment subjects to change behavior simply due to being in an experiment and not from any treatment

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19
Q

Detached Statistic

A

A claim using a statistic in which no comparison is made

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20
Q

Implied Connection

A

A claim that attempts to imply a connection between variables when there is not

(correlation =/= causation)

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21
Q

Frequency

A

The number of times a value appears in a data set

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22
Q

Relative Frequency

A

The number of times a value appears in a data set compared to other values

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23
Q

Ungrouped Frequency Distribution

A

A frequency table in which each data value gets its own section (as opposed to grouping similar but not equal values together)
(e.g. 1, 2, 3, etc. are all separate)

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24
Q

Grouped Frequency Distributions

A

A frequency table in which similar but not equal values are grouped together
(e.g. 1-10, 11-20, etc.)

25
Percentile
What percent of other values are less than the value being measured
26
Formula for finding percentile
(# of values below X + 0.5)/Total # of values
27
Symbols for percentile, deciles, quartiles
P = percentile D = Decile Q = Quartile
28
Symbol for median
MD
29
Interquartile Range / IQR
The difference between the first and third quartiles Used to identify outliers (1.5x beyond IQR=potential outlier)
30
Exploratory Data Analysis / EDA
A method of examining data in order to determine what can be discovered from it Makes few or no assumptions before this
31
Box plot
A number line with a box from the end of the first quartile to the third quartile, also featuring the MD
32
weighted Mean
A centerpoint found by multiplying each value by its corresponding weight, then dividing the sum of these products by the sum of the weights
33
Positively skewed Negatively Skewed
Mean is to the right of the median Mean is to the left of the median (Mode is on the opposite side)
34
Variance
The average of the squares of the distance each value is from the mean (Sum of [x thru y]^2)/N=σ²
35
Sample Variance
Adjusted average of variance, symolbized as s^2 (Sum of [x thru y]^2)/(N-1)
36
Bias
A systematic error that results in an overestimated or underestimated result
37
Chebyshev's theorem
The proportion of values of a data set will fall within k standard deviations of the mean will be at least 1-1/k^2, where k>1
38
Chebyshev's Rule
75% of values in a data set will be within 2 standard deviation of the mean 89% within 3 standard deviation, 95% within 4.5 standard deviation
39
Empirical/Normal Rule
In a normal distribution - 68% of values will be within one standard deviation of the mean - 95% within 2 - 99.7% within 3
40
Measures of Central Tendency
Measures of the center of a data set Mean, median mode
41
Measures of Variation
Measures of the spread of a data set Range, variance, sd
42
Position
Measure of the location of a data value percentiles, deciles, quartiles (norms)
43
Chance experiment
An experiment where the outcome is not predetermined (e.g. rolling dice)
44
Outcome
The result of a single trial of the experiment
45
Sample Space
The set of all possible outcomes of an experiment
46
Tree Diagram
Device used to list all possibilities of a sequence of events
47
Event
One or more outcomes of a probability event
48
Simple event
An event with only one outcome
49
Compound Event
An event with more than one poutcome
50
Classical Probability
Uses sample spaces to determined the numerical probability that an event will occur Assumes all outcomes of the sample space are equally likely to occur Always between 0 and 1 (e.g. dice)
51
Empirical Probability
Relies on actual experience to determine the likelihood of outcomes Not all events are equally likely (E.G. The odds someone voting for a candidate is a particular age)
52
Subjective Probability
Probability based on guestimate (e.g. chances a sports team will win a game)
53
Complement of an Event
The likelihood that an event does not occur (characterized by Ē)
54
Law of Large Numbers
The more data empirical probability draws from, the closer it resembles classical probability
55
Independent Event Dependent event
The outcome of the first event does not affect the outcome of the second The outcome of the first event does effect the outcome of the second
56
When in doubt, should you assume an event is dependent or independent?
Dependent
57
Permutation
An arrangement of n distinct objects in a distinct order Used when the order matters n!/(n-r)!
58

Spring 2025 (6 decks)

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