4.1 statistical analysis

Question 1

define mean

Answer 1

average; the middle point about which data points vary

Question 2

define standard deviation

Answer 2

measure of the variability/dispersion of a data set; range
low sd = data close to the mean
high sd= data is spread out

Question 3

define coefficient of variation

Answer 3

sd expressed as a %
(sd/mean) * 100

Question 4

define correlation

Answer 4

defines the relationship between two variables

Question 5

define t-test

Answer 5

measures whether there is a significant difference between two means

Question 6

state the distribution of data 1,2,3 standard deviations from the mean

Answer 6

1 sd: 68%
2 sd: 95%
3 sd: 99%

Question 7

explain how standard deviation is useful for comparing means and the spread of data between two or more samples

Answer 7

helps assess if mean differences are meaningful or random

Question 8

explain what scientists need to be careful about when describing and interpreting correlation

Answer 8

inferring that correlation is causation, its not

Question 9

outline the role of error bars in graphical data

Answer 9

represent a description of how confident you are that the mean represents the true value
the more original data values range about and below the mean, the wider the error bars, and the more confident you are in a particular value

Question 10

describe how to calculate the mean of a set of values

Answer 10

add up all the values, divide the sum by the number of values

Question 11

describe how to calculate the standard deviation of a set of values

Answer 11

stat, edit, values in L1
stat, calc, 1-var, enter

Question 12

describe how to calculate the coefficient of variation

Answer 12

divide the standard deviation by the mean, multiply by 100

Question 13

describe how to calculate the correlation of a data set

Answer 13

diagnostics on
stat, edit, x in LI, y in L2
stat, calc, 4:linreg

Question 14

describe how to complete a t-test

Answer 14

write out null and alternative hypotheses
stat, edit, 1st data in L1, 2nd data in L2
stat, tests, 2sampTtest, enter

Question 15

describe the difference between a one-tailed and two-tailed t-test

Answer 15

one-tailed: can only do one direction
two-tailed: difference between means can favor either mean

Question 16

describe the difference between a paired and unpaired test

Answer 16

paired: dependent, groups are related in some way
unpaired: independent, compares means to 2 independent means