Data and Measurement

Question 1

Accuracy

Answer 1

• how close the measurement is to its true value

Question 2

Precision

Answer 2

• how close a set of measurements are to each other

Question 3

Repeatability

Answer 3

• how close results will be if the experiment is replicated under the same conditions

Question 4

Reproducability

Answer 4

• how close the results will be to each other if the experiment is replicated under different conditions

Question 5

True Value

Answer 5

• the value of the measurement if it could be measured perfectly

Question 6

Quantitative Data

(3)

Answer 6

• uses numbers
  e.g. figures, statistics
• usually objective

Question 7

Qualitative Data

(3)

Answer 7

• uses words
  e.g. anecdotes, opinion
• usually subjective

Question 8

Internal Validity

(2)

Answer 8

• the extent to which the investigation actually investigates what it sets out/or claims to investigate
• improved by controlling extraneous variables, counterbalancing, validly operationalising variables

Question 9

External Validity

Answer 9

• the generalisability of the results to real-world settings
• improved by conducting the experiment in natural settings

Question 10

Standard Deviation

(3)

Answer 10

• how far the scores are spread out from the mean
  high s.d = high variation = low precision
  low s.d = low variation = high precision

Question 11

Error

Answer 11

• difference between the true value and the measured value

Question 12

Outliers

Answer 12

• scores which are extremely different from the rest
• may occur by random errors (chance)

Question 13

Uncertainty

Answer 13

lack of exact knowledge of the value of the quantity measured

Question 14

Random Error

(5) (chance)

Answer 14

• affect precision
• unpredictable
• results in spread of reading
• caused by limitation of instruments, environmental factors
• reduced by repeating measurements and calculating new mean, increasing sample size

Question 15

Systematic Errors

(4) (constant)

Answer 15

• affect accuracy
• differs measurement from true value by constant amount each time
• caused by observational errors, imperfect instrument calibration
• reduced by familiarity and experience with instruments

Question 16

Extraneous Variable

(4)

Answer 16

• variable other than the IV or DV that may cause a change in the DV and therefore may affect results in an unwanted way
• if left uncontrolled may become confounding variable
• threatens internal validity

Question 17

Confounding Variable

(3)

Answer 17

• variable that is not the IV/DV that has affected the DV and has effects that is indistinguishable from the IV’s effects thereby providing an alternate explanation for the results
• may have been an uncontrolled/cannot be controlled extraneous variable
• threatens internal validity

Question 18

Placebo Effect

(2)

Answer 18

• participants expectations on how to behave
• controlled by single blind (usually with placebo treatment)

Question 19

Experimenter Effect

(2)

Answer 19

• experimenter biasing interaction with participants/interpretation of results to be congruent with their hypothesis
• controlled by double blind

Question 20

Social Desiribility Bias

(2)

Answer 20

• over-report/exhibit socially desirable characteristics/behaviours
• under-report/inhibit socially undesirable characteristics/behaviours

Question 21

Uncertainty

Answer 21

lack of exact knowledge of the value of the quantity measured