Core Chapter 11: Sampling and Data

Question 1

State the 4 types of sampling errors

Answer 1

• Sampling error: characteristic of sample differs from characteristic of population (occurs even in samples randomly selected to avoid bias)
• Measurement error: errors in measurement at data collection stage
• Coverage error: sample does not accurately represent population (small or biased sample size)
• Non-response error: when large number of sample choose not to respond to survey

Question 2

State the 4 types of sampling methods

Answer 2

• Simple random sampling: Drawing lots/numbering population and using random number generator to select sample
• Systematic sampling: selecting members of population at fixed random intervals
• Convenience sampling: sample selected based on convenience of sampler
• Stratified/quota sampling: when population can be divided into sub-groups, and number of those selected from each sub-group correlates to the proportion of each sub-group relative to the entire population
  (Stratified sampling: if individuals from each strata are randomly selected)
  (Quota sampling: if individuals from each strata are specifically selected)

Question 3

State the 2 types of data

Answer 3

• Categorical data: data divided into categories
• Quantitative data: data involves numerical values
  (Discrete quantitative data: exact number values obtained by counting)
  (Continuous quantitative data: any numerical value within a certain range obtained by measuring)

Question 4

State how discrete numerical data can be presented differently using a column graph

Answer 4

Column graph
- Gaps between bars
- Mode can be identified
- Can have symmetric distribution, or be negatively or positively skewed, and can have outliers
- For data with many different data values with low frequencies: grouped discrete data (frequency of classes and modal class are identified)
(can be divided into class intervals)

Question 5

State how continuous data is presented

Answer 5

Histogram:
- No gaps between bars