Chapter 1 Flashcards Preview

Biostatistics > Chapter 1 > Flashcards

Flashcards in Chapter 1 Deck (54)
Loading flashcards...
1

What are the two criteria for a random sample?

1. Equal chance of being selected
2. Independent of each other

2

Explanatory variable

Independent variable
Predictor variable
Always on the x axis

3

Response variable

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

4

Frequency distribution

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

5

What is the criteria for a good sample?

Minimizing sampling error (precision )
Minimizing bias (accuracy)

6

Explanatory variable

Predictor variable

7

What 4 things do you look for when interpreting histograms?

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

8

Graph to make with 2 categorical variables

Grouped bar graph

9

Graph to make with one categorical and one numerical variable

Bar graph

10

What does standard deviation measure ?

Measure of how different values are from the mean

11

How is standard deviation calculated ?

The square root of variance

12

What is coefficient of variation ?

Expresses the standard deviation as a percentage of the mean

13

What happens when the coefficient of variation increases ?

There is more variability

14

What is IQR ? How is it calculated ?

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

15

Which measurement methods are more sensitive to extremes?

Standard deviation and mean !

16

What three things describe the shape of a distribution ?

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

17

What spread measurement is associated with median?

Inter quartile range

18

How do outliers affect mean? Median?

Mean increases
Median remains unchanged !

19

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

Mean is larger than the median

20

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

Mean = median

21

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

Mean

22

What part of the box plot represents the IQR ?

The entire box

23

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

Median line is closer to the top of the box

24

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

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