##### Biometry Chapter 3

0
Set Details Share
created 7 months ago by abmusser
3 views
updated 7 months ago by abmusser
show moreless
Page to share:
Embed this setcancel
COPY
code changes based on your size selection
Size:
X
1

Descriptive Statistics

Statistics that summarize the main characteristics of a sample of data

2

Three types of descriptive statistics

1. Sample size (n)

2. Measures of central tendency

3. Measures of variability

3

Measures of central tendency

Measures that summarize what the data in a sample are typically like.

4

Three measures of central tendency

1. Mean

2. Median

3. Mode

5

Mean The average number of a sample

- Affected by extreme values

6

Median The midpoint of a sample

- Less sensitive to extreme values

7

Mode

Number that occurs the most in a sample

- Not affected by extreme values

8

Measures of variability

Measures that summarize how similar the data in a sample are

9

Four measures of variability

1. Range

2. Interquartile range

3. Variance

4. Standard deviation

10

Range The difference between the smallest and largest values of a sample measuring the spread.

- Sensitive to extreme values

11

Interquartile range The difference between the lower and upper quartile ranges of a sample.

- Not very sensitive to extreme values

12

Variance The mean squared deviation from the mean

13

Sum of squares The sum of the squared deviations from the mean

14

Degrees of freedom

1 less than the sample size.

n-1

15

Standard deviation The square root of the variance

16

Frequency distributions

Show how many times different values occur in a sample

- table, graph, or histogram

17

1. Tail

2. Body

1. The extremes of a normal distribution

2. The middle section of the bell shaped curve

18

Parametric statistics

Statistics that rely heavily on the special properties of the normal distribution.

19

Pie Chart Chart showing the frequencies of a sample

20

Box Plot 21

How do you know if you have outliers on a box and whisker plot? Max value = UQ + (1.5 x IQR)

Min Value = LQ - (1.5 x IQR)

Any value above or below the max and min are outliers

22

Error bars Mean + standard deviation

Mean - standard deviation

23

On a graph where do the independent and dependent variables go? 24

What do the following axis labels mean?

1. Frequency

2. Relative frequency

1. The number of occurrences in a sample

2. The percent of occurrences in a sample

25

What are 4 types of distributions?

Normal

Binomial

Poisson

Uniform

26

What is a normal distribution? A bell shaped frequency distribution with a tail and a body

- 95% of the curve falls within 2 standard deviations of the mean

- No skew to the data

- Both tails go on for infinity

27

Binomial statistics

Collecting data from two nominal categories

- heads or tails

- dead or alive

- male or female

28

Poisson Statistics

Counting data that are whole numbers

- Number of eggs in a nest

- Number of cells in a petri dish