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MABS Research > Biostatistics II > Flashcards

Biostatistics II Flashcards

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1
Q

variable also known as_____?

A

data

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2
Q

any measurement that can have different values across individuals (e.g., height, weight, age, gender)

A

variable

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3
Q

what are the roles of a variable?

A 
predictor variable (Independent variable/Explanatory variable)
outcome variable(Dependent variable/Response variable)
confounding variable
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4
Q

Intervention/treatment/therapy is an example of what type of variable?

A

predictor variable

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5
Q

disease status is an example of what type of variable?

A

outcome variable

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6
Q

demographic information like age and gender are examples of what type of variable?

A

confounding variable

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7
Q

confounding variable is treated as what kind of variable in statistical modeling?

A

predictor variables

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8
Q

data that are measured in a numerical scale and are expressed as numbers

A

Quantitative

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9
Q

data that are described by words rather than numbers

A

Qualitative

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10
Q

Systolic and diastolic blood pressure, height, weight

this is what type of data?

A

quantitative data

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11
Q

open ended questions in surveys, eye color, Likert scale questions

this is what type of data?

A

qualitative data

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12
Q

quantitative data has these two types of classification?

A

discrete or continuous

interval or ratio

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13
Q

what are the categorical variables?

A

nominal
dichotomous
ordinal

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14
Q

what type of categorical variable has the following characteristics?

Labels
No order information

A

Nominal

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15
Q

what type of categorical variable has the following characteristics?

Only two possible labels
No order information

A

Dichotomous (a special case of Nominal)

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16
Q

what type of categorical variable has the following characteristics?

Order (rank) information is maintained
Differences/ratios do not make sense

A

Ordinal

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17
Q

blood type and occupation is what type of categorical variable?

A

nominal

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18
Q

Test result: Positive/Negative

is what type of categorical variable?

A

Dichotomous (a special case of Nominal)

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19
Q

Likert scale questions

Academic Tier is what type of categorical variable?

A

ordinal

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20
Q

what are the two types of quantitative variables? what are their subsets?

A

discrete and continuous

interval and ratio

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21
Q

this type of quantitative variable has the following characteristics?

Possible values are integers
Have acountablenumber of values

A

Discrete

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22
Q

this type of quantitative variable has the following characteristics?

Can have any value in a range

A

Continuous

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23
Q

Number of patients who were exposed to a risk factor
Number of patients who visited ER during last weekend

is an example of what type quantitative variable?

A

discrete

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24
Q

Amount of time between meal being served and onset of gastro-intestinal symptoms
Infant mortality rate

is an example of what type quantitative variable?

A

continuous

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25
Q

these subdivisions of discrete and continuous variables are these two types?

A

interval and ratio

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26
Q

interval or ratio has the following characteristics that are either interval or ratio?

No absolute zero exists
Differences make sense but not ratios
Only permits addition and subtraction

A

Interval

27
Q

interval or ratio has the following characteristics that are either interval or ratio?

Zero represents a true absence
Ratios make sense

A

Ratio

28
Q

this example:

Temperature in Celsius/Fahrenheit scale
IQ score (most standardized tests scores in psychology)

is interval or ration?

A

interval

29
Q

this example:

Temperature in Kelvin scale
Salary in $
Weight
Risk and proportion
is interval or ration?
A

ratio

30
Q

what should we consider when determining the type of a variable?

A

the research context and how it was measured

Example: Age by nature is continuous and ratio, but it may be of other types:
Age as ordinal: Age group 0-17, 18-60, 60+
Age as discrete: age at the last birthday, age on the day of medical school interview

31
Q

what are the tools used in descriptive statistics?

A

numerical measurements

graphical tools

32
Q

what is the tool used from descriptive statistics derived from these examples?

Measures of central tendency
Measures of dispersion

A

numerical measurements

Tools to choose depend on the type of variables

33
Q

what is the tool used from descriptive statistics derived from these examples?

Frequency table
Bar chart/Pie chart
Histogram/Box plot
Scatterplot

A

graphical tools

Tools to choose depend on the type of variables

34
Q

what are the measures of central tendency?

A

mean
median
mode

35
Q

this measure of central tendency is an average of all values?

A

mean

36
Q

this measure of central tendency is the middle value of the ordered dataset?

A

median

37
Q

this measure of central tendency is the most commonly used value?

A

mode

38
Q

this measure of central tendency is used:

Not robust to extreme values
Makes most sense for quantitative variables

A

mean

39
Q

this measure of central tendency is used:

Robust to extreme values
Makes most sense for quantitative variables
Can also be used for ordinal variables

A

median

40
Q

this measure of central tendency is used:

Can be used to describe both categorical and quantitative variables
Can have more than one modes

A

mode

41
Q

which of the following measures of central tendencies is applicable only to females?

A

mode

42
Q

which of the following measures of central tendencies is applicable to age?

A

mean and median

43
Q

what are the four measures of central tendencies?

A

variance
standard deviation
range
interquartile range

44
Q

what is variance?

A

How close the values are to the mean

45
Q

what is standard deviation?

A

Square root of variance

46
Q

what is range?

A

Max value – min value

47
Q

what is interquartile range?

A

𝑄3-𝑄1

48
Q

these measures of dispersions are used:

Not robust to extreme values
Makes most sense for quantitative variables

A

variance
standard deviation
range

49
Q

this measure of dispersion is used:

Robust to extreme values
Makes most sense for quantitative variables

A

Interquartile Range

50
Q

A table listing the possible values for a variable, together with their (relative) frequencies.

A

frequency table

51
Q

this type of table is used when:

for categorical variables

measures number of times the observations fall into a certain category
relative

frequency=frequency/total

A

frequency table

52
Q

a circular diagram divided into segments, each representing a category of the variable.

A

Pie Chart

53
Q

a type of graph for presenting categorical variable in such a way that each observation can fall into one and only one category of the variable.

A

Bar Chart

54
Q

a graphical representation of the frequency distribution of a quantitative variable.

A

Histogram

55
Q

the significance of a histogram is to allow the inspection of the data for its underlying distribution, outliers, skewness, etc.

A

Histogram

56
Q

what are the following steps used to construct?

Step 1: split the data into intervals, called bins.
Step 2: use the table from step 1 to construct the histogram.

A

histogram

57
Q

this type of plot is used to present the distribution of a variable measured on a numerical scale (discrete or continuous).

why?

A

Box plot

It allows easy inspection of potential outliers and group comparisons (side-by-side box plot).

58
Q

the following is a guideline to use when it comes to potential outliers?

Any point below the lower extreme/fence (𝑄_1βˆ’1.5𝐼𝑄𝑅)

Any point above the upper extreme/fence

(𝑄_3+1.5𝐼𝑄𝑅)
IQR=Q3-Q1

A

Criteria for potential outliers (indicated by β€œβˆ™β€ or β€œβˆ—β€)

59
Q

what is the significance of a box plot?

A

Side-by-side box plot allows visualization of group comparisons.

its usually drawn out before working out a correlation or fitting a regression line

60
Q

pattern
direction
strength
anomalies

these are indications for a _____ (what type of plot)?

A

scatterplot

61
Q

this definition defines a variable of what to look for in a scatterplot?

clusters of points or outliers like outliers and clusters

A

anomalies

62
Q

this type of anomaly consists of points that deviates from the overall pattern

A

outliers

63
Q

this type of anomaly consists of groups of points separated from one another

A

clusters

64
Q

how do we define the scatterplot trends?

A

strong, positive, liners
no overall
strong, quadratic
clustered

MABS Research (5 decks)

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