Reading for week 2 - Chapter 5, Data and Variables

Question 1

define variable

Answer 1

any characteristic that can be measured or experimentally controlled on different items or objects

Question 2

define dataset

Answer 2

a group of related variables

Question 3

the variables in a dataset can often be classified as either…

Answer 3

numerical or categorical

Question 4

numerical variables can be further classified into…

Answer 4

interval and ratio scales

Question 5

categorical variables can be further classified into…

Answer 5

nominal and ordinal variables

Question 6

what is a nominal variable?

Answer 6

a variable in which no natural ordering relative to one another occurs within the observations

Question 7

what is ordinal data?

Answer 7

data in which the observations can be assigned a meaningful order, but where the exact distance between items is not fixed, or even known

Question 8

what are interval scale variables?

Answer 8

variables that have a consistent numerical order but the scale starts at an arbitrary point e.g. degrees celsius - scale starts at an artificial zero (the freezing point of water)

Question 9

what are ratio scale variables?

Answer 9

these have a true zero and consistent mathematical relationship between any point on the measurement scale

Question 10

discontinuous data

Answer 10

also referred to as discrete
means that only certain values are possible in the original data
e.g. count data - number of eggs in a nest, number of heartbeats per minute; these can only comprise of whole numbers

Question 11

continuous data

Answer 11

numerical and allows non whole numbers to occur in the data

e.g. gas flux data, weight

Question 12

define accuracy

Answer 12

how close a measurement is to the true value of whatever it is you are trying to measure

Question 13

precision

Answer 13

how repeatable a measure is, irrespective of whether it is close to the actual value

Question 14

define bias

Answer 14

a systematic lack of accuracy