# Australian Bureau of Statistics

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 Understanding statistics

Data awareness

Q1. Which of the following is the correct logical order for these terms?
1. Knowledge - Data - Information - False
2. Data - Information - Knowledge - Correct
3. Knowledge - Information - Data - False
4. Information - Data - Knowledge - False

Q2. What is Australia's official population count?
1. Census - False - Census is good at gathering information about the characteristics of the population, but it is not good at providing an authoritative population count.
2. Estimated Resident Population - This is correct. The Estimated Resident Population (ERP) is the official Australian Bureau of Statistics estimate of the Australian population. The ERP is based on the five-yearly Census, updated for the components of population growth (births, deaths, interstate migration, overseas migration).
3. Labour Force Survey - False - The Labour Force Survey provides information about employment.
4. Population 101 - False.

Understand statistical concepts

Q3. Which of the following is not a measure of central location?
1. mean - False - the mean can provide a measure of central location to describe the distribution of the data.
2. range - This is correct! - The range is not a measure of location, but instead can provide a summary measure to indicate the variability of data.
3. median - False - the median can provide a measure of central location to describe the distribution of the data.
4. quartiles - False - quartiles can provide a measure of location to describe the distribution of the data.

Q4. A local milk-bar owner records how many customers enter the store over a 5 day period. The number of customers is as follows: 20, 21, 23, 21, 26. What is the mode of this survey?

a. 20 - False - the mode is the most frequently occurring observation, and over the 5 days, only on one occasion did 20 customers enter the store.
b. 21 - You're correct - the mode is the most frequently occurring observation, which in this case is 21 which occurred twice, while all other observations only occurred once.
c. 23 - False - the mode is the most frequently occurring observation, and over the 5 days, only on one occasion did 23 customers enter the store.
d. 26 False - the mode is the most frequently occurring observation, and over the 5 days, only on one occasion did 26 customers enter the store.

Q5. Complete the following. ___________ is the process of estimating and then removing from a time series influences that are systematic and calendar related.
1. Trend - False - The ABS trend is defined as the 'long term' movement in a time series without calendar related and irregular effects, and is a reflection of the underlying level.
2. Stock series - False - A stock series is a measure of certain attributes at a point in time and can be thought of as “stocktakes”.
3. Seasonal adjustment - Correct! - Observed data needs to be seasonally adjusted as seasonal effects can conceal both the true underlying movement in the series, as well as certain non-seasonal characteristics which may be of interest to analysts.
4. Flow series - False - Flow series are series which are a measure of activity over a given period.

Analyse, interpret and evaluate statistical information

Q6. If a company has a workforce of 2,700 people, and a sample of 300 people were to be systematically surveyed, what would the sampling interval be?
1. 300 - False
2. 90 - False
3. 30 - False
4. 9 - Correct

Q7. Assume that the population of a school is 2,000. A survey found that only 30% of students in the school exercised on a regular basis. How many students exercise regularly?
1. 2,600 people - Oops you have found how many people there would be if the population increased by 30%. Additionally, when reading a question look at the wording. A giveaway is the use of the word of, this symbolises that you need to multiply.
2. 1,400 people - Be careful you have just found out what 70% of the population is by subtracting 30%. To find a percentage of a given figure you need to multiply that number by the percentage.
3. 6 people - You have made a simple calculation error. Instead of finding 30% (0.30) you have found 3% (0.03). Always be careful when transferring a percentage to a decimal. Please read module one again if you are unsure.
4. 600 people - That's correct! You successfully understood that to find a percentage of a given figure, you multiply that figure by the percentage (2000*0.3 = 600)

Q8. Based on the table of figures below, what is the total unemployment percentage for March, rounded to a whole number?

 Labour Force Population Unemployment rate Male 53,000 6% Female 58,000 8% Total 111,000 ?

1. 14% - Incorrect, you must be careful it is a common mistake for people to just add percentages however these two groups have a different population therefore this is not a simple calculation. You need to find out how many males and females are unemployed at each percentage rate, then add these two figures together. This total figure is then divided by 111,000 and multiplied by 100.
2. 7% - That's correct. The total number of males unemployed is 53,000 * 0.06 = 3,180. The total number of females unemployed is 58,000 * 0.08 = 4,640. With a total unemployment of 7,820 people. Therefore, the total percentage of unemployment is (7,820/111,000) * 100 = 7.05%
3. 67% - This is a common error to make. You have done the calculations correctly however you have calculated using the wrong percentage Eg: 53,000 * 0.6 (60%) when it should have been 53,000 * 0.06 (6%). Try this one again.
4. 5.5% - Sorry that is incorrect. You have found what the male unemployment percentage is of the female population. Instead you need to find out how many males and females are unemployed at each percentage rate, then add these two figures together for the total unemployment. This total figure is then divided by 111,000 and multiplied by 100.

Communicate statistical information and understandings

Q9. When house prices are referred to in newspapers, what would be the most accurate way to represent these?
1. Median - Correct - the median value provides a much more accurate picture of house prices.
2. Mean - False
3. Mode - False
4. Average - False