Question

Consider the following statement: The proportion of all students enrolled at a particular university during 2012 who lived on campus was \(\mathbf{0 . 2 1}\). a. Is the number that appears in boldface in this statement a sample proportion or a population proportion? b. Which of the following use of notation is correct, \(p=0.21\) or \(\hat{p}=0.21 ?\)

Short answer

a. The number 0.21 is a population proportion. b. The correct notation is \(p=0.21\).

Step-by-step solution

Identify the Proportion Type

Consider the boldface number, which is 0.21. This represents the percentage of all students enrolled at that university in 2012 who lived on campus. Since it represents all the students for that year, it is a population proportion, not a sample proportion. A population proportion represents data from every individual in a group, while a sample proportion involves data from just a subset.

Select the Correct Notation

Next, consider the correct notation for the proportion. The notation \(p\) is used for a population proportion, while \(\hat{p}\) is used for a sample proportion. Since we've determined that 0.21 is a population proportion, the correct notation is \(p=0.21\).

Key concepts

Sample Proportion

When conducting a survey or a study, it's often impractical to collect data from every individual within a larger population. Instead, researchers select a smaller group, known as a sample, to represent the whole. The sample proportion, denoted by \(\hat{p}\), is a statistic that estimates the proportion of a particular outcome from this smaller subset.

For example, if a survey was conducted on the eating habits of students and 60 out of 200 surveyed students said they are vegetarian, the sample proportion of vegetarians would be \(\hat{p} = \frac{60}{200} = 0.30\). This provides an estimate, but not an exact measure, of the vegetarian population within the entire student body.

To ensure accuracy, the sample must be representative of the population. This often involves random sampling techniques and can be affected by the sample size. Larger sample sizes typically yield more reliable proportions, thus helping to infer the characteristics of the full population.

Proportion Notation

In statistics, clear and consistent notation is key to understanding data representations. Proportion notation is a symbolic way to express the relationship between parts of a group and the whole. The population proportion, denoted by \(p\), represents the actual proportion in the entire population. It is a fixed value, although in practice, it is often unknown and has to be estimated using a sample proportion.

For instance, if a study finds that out of all the trees in a forest, 40% are pine trees, the proportion notation would be \(p = 0.40\). This proportion is an exact number and doesn't change unless the actual population changes. In contrast, a sample proportion, denoted by \(\hat{p}\), would be used if only a part of the forest was studied to estimate the proportion of pine trees. The understanding and correct application of these notations is crucial for accurate statistical communication and analysis.

Statistical Notation

Statistical notation is the standardized language used in mathematics and statistics to succinctly represent quantities, operations, and relations. It provides a universal shorthand that can precisely convey complex ideas. For example, Greek letters like \(\mu\) and \(\sigma\) often represent population mean and standard deviation, respectively.

Understanding statistical notation is essential for interpreting the results of data analyses. For instance, \(p\) and \(\hat{p}\) differ significantly in meaning: one describes a population proportion and the other a sample proportion. Failure to recognize which proportion is being used can lead to misunderstandings or errors in the conclusions drawn from the data.

Other common notations include \(n\) for sample size, \(\bar{x}\) for sample mean, and \(s\) for sample standard deviation. Each symbol is an integral part of the statistical narrative, helping to weave a clear and consistent picture from raw data to final analysis.