What is the difference between statistical and non

What is Non-Statistical Sampling?

Non-statistical sampling is the selection of a test group that is based on the examiner's judgment, rather than a formal statistical method. For example, an examiner could use his own judgment to determine one or more of the following:

• The sample size

• The items selected for the test group

• How the results are evaluated

To reduce the amount of variability in a non-statistically determined sample size, an examiner usually refers to a table that sets forth the approximate sizes to be used. For example, a low-risk situation may call for the selection of 25 records, while a high-risk situation might mandate the selection of 100 records.

When using a non-statistical approach to select the items for a test group, the examiner should not introduce too much bias into the selections. For example, do not lean too heavily on supplier invoices where the invoice amount exceeds $10,000 and the name of the supplier begins with a "P". Instead, the selection should come as close as possible to representing the entire population of records.

When to Use Non-Statistical Sampling

It can make sense to use non-statistical sampling when the population size is very small. In this case, it is not efficient to spend the extra time to set up a statistical sample. This approach is also useful in areas where specific records contain sensitive information, and so must be examined. For example, an examiner might want to select the invoices of specific law firms, because these firms deal with environmental obligations, which may involve substantial liabilities.

Statistical Questions

Alignments to Content Standards: 6.SP.A.1

Task

Last night, Jennifer and her family went out for dinner. The questions below came up on their way to the restaurant or during the meal. Decide whether or not each question is a statistical question, and justify your decision.

1. How far are we from the restaurant?
2. How long will it be until we get there?
3. Would Jennifer rather have burgers or pizza?
4. How much should we leave for the tip?
5. What was the first dish ordered in the restaurant this evening?
6. Do customers at the restaurant like pizza?
7. What is a typical bill for tables at this restaurant?
8. On average, how many people were sitting at each table this evening?

IM Commentary

The goal of this task is to promote a discussion of what makes a statistical question. This is an ideal place for a classroom discussion because answers are not always clear cut and there is a continuum going from questions that are clearly not statistical (Who was the King of France in 1716?) to questions that are definitely statistical (What is the average lifespan in the United States?). There is a lot of ground in between because a question can be interpreted and answered in different ways. A statistical question is one that can be answered by collecting data and for which there will be variability in that data. Questions that are answered with a single data point are not statistical questions because there is no variability in the data used to answer the question.

Solution

1. This is not a statistical question if the route to the restaurant is determined or if the question is intended ''as the crow flies''. In these cases, it would be a fixed numerical answer, which is likely what is intended by the question. It could be viewed as a statistical question if it referred to time rather than distance (e.g. On average, how long does it take to get home from the restaurant?). 
2. Unlike the first question, this is a statistical question. Variables such as traffic signals and the amount of traffic rule out an exact answer. The answer will be an approximation based on repeated experience of similar conditions and drives. That is, the answer would be based on data that vary.
3. This question refers to a single person and so it would be answered based on a single response and not on data that vary.
4. This could be a non-statistical question if, for example, the family always leaves a fixed percent of the bill for a tip. On the other hand, there may be a discussion and consideration of how much everyone enjoyed the meal and service with each person suggesting a tip amount. This would make it a statistical question.
5. This is not a statistical question. The first dish ordered is a fixed item and this question would not be answered by collecting data that vary.  
6. This is a statistical question (unless we know in advance that everyone is going to say yes or no).
7. This is a statistical question. It would be answered by collecting data on the amount of the bill for different tables, and this amount would vary from table to table.  
8. Like the previous question, this is a statistical question. It would be answered by collecting data on the number of people at a table form many tables and there would be variability in the data collected. 

Statistical Questions

Last night, Jennifer and her family went out for dinner. The questions below came up on their way to the restaurant or during the meal. Decide whether or not each question is a statistical question, and justify your decision.

1. How far are we from the restaurant?
2. How long will it be until we get there?
3. Would Jennifer rather have burgers or pizza?
4. How much should we leave for the tip?
5. What was the first dish ordered in the restaurant this evening?
6. Do customers at the restaurant like pizza?
7. What is a typical bill for tables at this restaurant?
8. On average, how many people were sitting at each table this evening?

What does non

What is a non

How do you know if a question is statistical or not?

What are the three main parts of statistical and non