Simple Statistical Statements
a. Almost all squirrels in Vancouver are black.
b. 75 per cent of the books used were second hand.
Astandard form for statistical statements:
(percentage) of (population) has (property)
The Standard Pattern for SurveyArguments
Sample population: the limited group of people surveyed,
Target population: the larger group about which the conclusion is drawn is galled
Sample population: 500 households in Burnaby.
Premise in the standard form for statistical arguments:
40 per cent of the 500 households surveyed correctly used the recycling bins.
Target Population: The residents of Burnaby.
Conclusion in the form of a simple statistical statement:
40 per cent of the residents of Burnaby correctly use the recycling bins.
Suppose instead the survey was as follows:
Example 2 The conclusion was that 80% of Burnaby residents correctly recycled
*Example 2 relies on people saying what they are in do, rather than their actions
being directly measured as with Example 1.
This means that the property measured in Example 1 is different from that measured
in Example 2.
Measured property in a survey argument is the property actually measured in the
survey. The property you are interested finding out about is called the target
property. In Example 1, measured property and target property are the same:
Preliminary Pattern for SurveyArguments:
1. Result of sample: x per cent of the sample population has the measured
property (EP) or (IP)
2. Conclusion about sample: x percent of the sample property has the target
3. Final conclusion: x per cent of the target population has the target property (1,
Representativeness premise(the sample is representative of the target population): a
premise linking the sample population to the target population.
Expanded Pattern for Survey Arguments:
The background information is not a premisebut it is important in evaluating
premises 2 and 4.
In reconstructing survey arguments, there is no need to write out 2 and 4. You can use their names-Accuracy premise, Representativeness premise
Example2 in Expanded Standard Form
Background information: 500 shoppers in Metrotown Shopping Mall were
interviewed on one Saturday in February. They were asked if they followed the
correct procedure for recycling houehold paper and containers. (EP or IP)
a) 80% of the shoppers surveyed said they followed the correct recycling
b) Accuracy premise (IP)
c) 80% of the shoppers surveyed followed the correct recycling procedures. (1, 2)
d) Representativeness premise (IP)
e) 80% of the residents of Burnaby follow the correct recycling procedures.(3, 4)
Evaluation consists in evaluating the premises. Criticisms must be directed at 1, 2
1. Evaluating Sample Results – premise 1: the only reason to criticize this
premise will be if you think the results have been misreported: so follow the
standards for testimonial arguments.
2. Evaluating theAccuracy Premise – when they are distinct, whether the
measured property is an accurate measure of the target property varies from
case to case. The background information will help you decide whether it is
reasonable to believe. Reasons to think the measured property may not be a
good indicator of the target property:
• dishonest survey