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Biostatistics > Chapter 1 > Flashcards

Chapter 1 Flashcards

(54 cards)

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1
Q

What are the two criteria for a random sample?

A
  1. Equal chance of being selected

2. Independent of each other

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2
Q

Explanatory variable

A

Independent variable
Predictor variable
Always on the x axis

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3
Q

Response variable

A

Dependent variable. What is being measured ? What do we want to predict ? Always on the y axis

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4
Q

Frequency distribution

A

Number of times each value of a variable occurs in a sample

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5
Q

What is the criteria for a good sample?

A 
Minimizing sampling error (precision ) 
Minimizing bias (accuracy)
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6
Q

Explanatory variable

A

Predictor variable

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7
Q

What 4 things do you look for when interpreting histograms?

A

Over all pattern?
What is the shape?
What is the spread?
Any striking deviations?

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8
Q

Graph to make with 2 categorical variables

A

Grouped bar graph

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9
Q

Graph to make with one categorical and one numerical variable

A

Bar graph

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10
Q

What does standard deviation measure ?

A

Measure of how different values are from the mean

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11
Q

How is standard deviation calculated ?

A

The square root of variance

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12
Q

What is coefficient of variation ?

A

Expresses the standard deviation as a percentage of the mean

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13
Q

What happens when the coefficient of variation increases ?

A

There is more variability

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14
Q

What is IQR ? How is it calculated ?

A

Inter quartile range = difference between the first and third quartile.

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15
Q

Which measurement methods are more sensitive to extremes?

A

Standard deviation and mean !

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16
Q

What three things describe the shape of a distribution ?

A

Symmetric or asymmetric ?
Center of data ?
Spread of data ?

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17
Q

What spread measurement is associated with median?

A

Inter quartile range

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18
Q

How do outliers affect mean? Median?

A

Mean increases

Median remains unchanged !

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19
Q

How does the mean relate to the median if the data is left skewed ?

A

Mean is larger than the median

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20
Q

How are mean and median related when the spread is symmetrical ?

A

Mean = median

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21
Q

What measure of location should be used if the distribution is symmetrical ?

A

Mean

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22
Q

What part of the box plot represents the IQR ?

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A

The entire box

23
Q

What will a box plot look like if it is left skewed ?

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A

Median line is closer to the top of the box

24
Q

What will a box plot look like if it is right skewed ?

Study These Flashcards
A

The median line is closer to the bottom of the box

25
Explanatory variable
Predictor variable
26
What 4 things do you look for when interpreting histograms?
Over all pattern? What is the shape? What is the spread? Any striking deviations?
27
Graph to make with 2 categorical variables
Grouped bar graph
28
Graph to make with one categorical and one numerical variable
Bar graph
29
What does standard deviation measure ?
Measure of how different values are from the mean
30
How is standard deviation calculated ?
The square root of variance
31
What is coefficient of variation ?
Expresses the standard deviation as a percentage of the mean
32
What happens when the coefficient of variation increases ?
There is more variability
33
What is IQR ? How is it calculated ?
Inter quartile range = difference between the first and third quartile.
34
Which measurement methods are more sensitive to extremes?
Standard deviation and mean !
35
What three things describe the shape of a distribution ?
Symmetric or asymmetric ? Center of data ? Spread of data ?
36
What spread measurement is associated with median?
Inter quartile range
37
How do outliers affect mean? Median?
Mean increases | Median remains unchanged !
38
How does the mean relate to the median if the data is left skewed ?
Mean is larger than the median
39
How are mean and median related when the spread is symmetrical ?
Mean = median
40
What measure of location should be used if the distribution is symmetrical ?
Mean
41
What part of the box plot represents the IQR ?
The entire box
42
What will a box plot look like if it is left skewed ?
Median line is closer to the top of the box
43
What will a box plot look like if it is right skewed ?
The median line is closer to the bottom of the box
44
What causes outliers?
Natural variation Human error in recording Human error in experimentation
45
What is the observational unit ?
The subject that is being tested on
46
How does the sample size affect a sampling distribution ?
If the sample size is increased then there will be less variation in the sample distribution. Precision is increased
47
What does sampling distribution measure ?
Precision of an estimate
48
What happens to the standard error of the mean as the sample size increases ?
As the sample size increases the standard error of the mean decreases
49
Formula for SE?
S/ (square root of n)
50
What does standard error describe?
The spread of the distribution of the sample means. Aka precision.
51
What happens to standard deviation as sample size increases ?
The sd becomes more | Precise
52
Name two measures of uncertainty
Confidence interval and standard error of the mean
53
What is the unit of replication ?
Wherever the treatment is applied
54
What does the confidence interval do ?
Quantifies the uncertainty about values

Biostatistics (2 decks)

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