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Statistical Methods > Lecture 1 > Flashcards

Lecture 1 Flashcards

1
Q

What is a variable?

A

a characteristic of a unit that may vary for different observations

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2
Q

What are the two main types of variables (they each go by 2 terms)?

A

qualitative (categorical) & quantitative (numerical)

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3
Q

Qualitative uses which 2 scales of measurement?

A

nominal & ordinal

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4
Q

Nominal

A

order does not matter e.g. gender

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5
Q

Ordinal

A

order does matter e.g. education levels

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6
Q

Quantitative uses which 2 scales of measurement?

A

interval & ratio

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7
Q

Interval

A

difference of quantities that are meaningful but ratios of quantities cannot be compared e.g. temperature in C

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8
Q

Ratio

A

ratios of quantities that are meaningful

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9
Q

What is an observational study?

A

the investigator observes a variable of interest of an existing sample in order to draw conclusions

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10
Q

What is an experimental study?

A

the investigator examines how a response variable behaves when the researcher manipulates one or more factors to determine the effect of those factors on the response

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11
Q

Cross-sectional data

A

data collected at the same or approximately the same point in time

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12
Q

Time series data

A

data collected over several time periods

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13
Q

Spatio-temporal data

A

data collected at different locations over several time periods

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14
Q

Statistical sampling

A

the procedure to select a subset from a statistical population that is representative of the population

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15
Q

Frequency for a particular category

A

the number of times the category appears in the data set

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16
Q

Relative frequency for a particular category

A

the fraction or proportion of the time that the category appears in the data set

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17
Q

How are qualitative (categorical) variables typically summarized/visualized?

A

frequency table, bar chart & pie chart

18
Q

Frequency table

A

displays the possible categories along with the associated frequencies or relative frequencies

19
Q

How are quantitative (numerical) variables typically summarized/visualized?

A

stem-and-leaf plot, histogram & box-and-whisker plot

20
Q

What does a measure of center attempt to do?

A

report a typical value for the variable e.g. mean, median & mode

21
Q

What is it called when a measure of center is calculated with sample data?

A

statistic

22
Q

What is it called when a measure of center is calculated with popular (e.g. census data)?

A

parameter

23
Q

What is the population mean, how is it denoted & what is its formula?

A

denoted by mu_x, it is the sum of all the population values divided by the size of the population (N) [insert image]

24
Q

What is the sample mean, how is it denoted & what is its formula?

A

denoted by Xbar, it is the sum of all the sample values divided by the sample size (n) [insert image]

25
Q

Median

A

the value separating the higher half from the lower half of a data sample

26
Q

Mode

A

the value of the observation that appears the most frequently

27
Q

What are the measures of spread?

A

range, variance/standard deviation & interquartile range (IQR)

28
Q

Range

A

the difference between the largest and smallest values in a dataset

29
Q

What is the sample standard deviation, how is it denoted & what is its formula?

A

denoted by s, it is a measure of the amount of variation of data [insert image]

30
Q

How is the sample variance denoted, what is its relationship to the sample standard deviation & what is its formula?

A

denoted by s^2, it is the sample standard deviation squared [insert image]

31
Q

The sample standard deviation can be used as the estimate of the…

A

population standard deviation

32
Q

Population standard deviation symbol

A

sigma

33
Q

Population variance

A

sigma^2

34
Q

IQR

A

Q_3 - Q_1

35
Q

Q_1

A

the median of the lower half of the data (lower quartile)

36
Q

Q_3

A

the median of the upper half of the data (upper quartile)

37
Q

Percentile

A

a value such that at least p% of the data set is less than or equal to this value (e.g. 25th percentile = Q1)

38
Q

Lower Fence (LF)

A

Q1 - 1.5 IQR

39
Q

Upper Fence (UF)

A

Q3 + 1.5 IQR

40
Q

Scatterplot

A

useful tool to graphically display the relationship between 2 numerical values (each dot represents one observation)

Statistical Methods (3 decks)

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