Basic Statistics I (3)

Question 1

What are indices of central tendency?

Answer 1

describe the typical or central value in a distribution

mean, median, mode

Question 2

What is the mean?

Answer 2

sum of observations / number of observations

Question 3

What is the median?

Answer 3

the level below or above half of the observations

50th percentile

Question 4

What is the mode?

Answer 4

the most frequent occurrence of observations

the number that appears the most is the mode

Question 5

Is this positively or negatively skewed?

Answer 5

negatively skewed

Question 6

Is the mean or median better for skewed data? Why?

Answer 6

median

outliers can skew the mean

Question 7

What is probability?

Answer 7

the numerical expression of the likelihood of occurrence

or what the chances something will happen are

Question 8

What is simple probability?

Answer 8

the likelihood of one event occurring

ex. dice problem

Question 9

What is conditional probability?

Answer 9

looks at two events occurring in relation to one another

looks at the probability of a second event occurring based on the probability of the first event occurring

Question 10

What are complex probability multiplication and addition rules?

Answer 10

used to calculate the probabilities of independent events

first, when both events occur (A and B)

second, when either event occurs (A or B)

Question 11

What is an independent event?

Answer 11

those events whose occurrence is not dependent on any other event

• can occur at the same time as another event

Question 12

What does mutually exclusive events mean?

Answer 12

events that cannot occur at the same time

Question 13

What is the multiplication rule?

Answer 13

used to calculate the probability of independent events both occurring

Pr(A and B) = Pr(A) x Pr(B)

Question 14

Two people roll one dice each. What is the probability that they both roll a 4?

Answer 14

1/6 x 1/6 = 1/36

Question 15

When is the addition rule of probability used?

Answer 15

mutually exclusive events

Question 16

What is the addition rule?

Answer 16

used to calculate the probability of independent events either occurring (A or B)

Question 17

You roll one dice. What is the probability that you roll a 3 OR a 6?

Answer 17

1/6 + 1/6 = 2/6 or 1/3 = 33.3%

Question 18

What is the addition rule Pr A or B?

Answer 18

when NOT mutually exclusive

both can happen at the same time

Pr (A) + Pr (B) - Pr (A and B)

Question 19

What is a target population?

Answer 19

the population to which it might be possible to extrapolate results from a study

Question 20

What is a study/source population?

Answer 20

the population from which the study subjects are drawn

Question 21

What is a sampling frame?

Answer 21

are available and we are able to sample

Question 22

What is a sample?

Answer 22

consists of the individuals (animals or groups of animals) that end up in the study

Question 23

T/F: All measurements are susceptible to error

Answer 23

TRUE

Question 24

What are the two types of measurement errors?

Answer 24

random error (imprecision)

systematic error (bias)

Question 25

What is sampling error? It is a type of _____ error

Answer 25

is a bias in which a sample is collected in such a way that some members of the intended population have a lower or higher sampling probability than others

systematic error

Question 26

How do you reduce systematic bias?

Answer 26

through random sampling

a selection process that gives each member of the population being studied an equal chance to be chosen

Question 27

What are the 4 types of random sampling?

Answer 27

simple random sample
systematic sample
stratified sample
cluster sample

Question 28

What does random sampling attempt to achieve?

Answer 28

replicate characteristics of the target population using a sample

Question 29

T/F: Unbiased random sampling guarantees a replication of Target Population characteristics

Answer 29

FALSE

Question 30

What is standard error of measurement? What is it also called?

Answer 30

the variability of a simple statistic

also called random error

Question 31

What are confidence intervals?

Answer 31

surround point estimate with margin of error

ex. a 95% CI for a mean has a 95% chance of capturing the “true” mean

Question 32

What does CI width do?

Answer 32

quantifies precision of the estimate

Question 33

What do confidence intervals only address?

Answer 33

random error only