Question

Some people have been complaining that the children's playground at a municipal park is too small and is in need of repair. Managers of the park decide to survey city residents to see if they believe the playground should be rebuilt. They hand out questionnaires to parents who bring children to the park. Describe possible biases in this sample.

Short answer

The sample is biased because it only includes parents who use the park, potentially skewing opinions.

Step-by-step solution

Understand the Scenario

We are examining a scenario where park managers want to determine if a playground should be rebuilt. This decision is based on survey responses from park visitors.

Identify the Population of Interest

The population of interest includes all city residents who may have an opinion about whether the park's playground should be rebuilt. This encompasses individuals who may not visit the park but still have a stake in city planning and amenities.

Analyze the Sampling Method

Understand that the park managers are surveying only parents who bring children to the park. This means they are not reaching out to the broader city resident population.

Identify Potential Biases

The sample is likely to be biased because it only includes parents who already visit the park. Their experiences may differ from those who do not use the park, leading to an overrepresentation of particular opinions, especially of those already utilizing or directly affected by the park’s condition.

Discuss the Effects of the Bias

The bias may lead to skewed results which may not reflect the views of the broader community. Parents using the park may have stronger preferences for improvement compared to other residents.

Key concepts

Survey Methodology

Survey methodology is the strategic framework used to gather data from a specific group in order to answer a question or set of questions. In the context of our playground scenario, the managers chose a method that surveys park visitors through questionnaires. Surveying is a popular way to include standard questions that respondents answer. This allows researchers to collect structured data easily.

However, the way this data is collected can heavily influence the results. For instance, using only face-to-face questionnaires at the park might not encompass a wide range of city residents. This is a limitation of the chosen survey methodology. To improve, managers could explore alternative methods like online surveys, which can reach participants who do not visit the park in person. Additionally, different types of questions, such as open-ended ones, can provide more detailed opinions and insights from respondents.

Population Sampling

Population sampling refers to the process of selecting a group of individuals from a larger population to participate in a survey. In our exercise, the population of interest is all city residents who may have opinions about the playground.

The sample taken by the park managers focuses only on parents at the playground. This is not a random or representative sampling of the whole city. It misses out on those who might have valuable input but do not visit the playground. To get a more accurate reflection, it's often better to use a variety of sampling methods, such as:

• Random Sampling: Each member of the city has an equal chance of selection, preventing biases.
• Stratified Sampling: Divides the population into groups (e.g., based on neighborhoods or user demographics) and samples from each group.
• Convenience Sampling: Using an easy-to-reach population segment, though this risks bias, as seen in the managers' method.

A more inclusive approach could provide a more balanced view of public opinion on the playground issue.

Bias in Surveys

Bias in surveys occurs when the survey results do not accurately represent the population's views due to systematic errors in data collection. This exercise highlights bias as it results in opinions from only a section of the community - parents who visit the park.

Such bias might skew results, suggesting perhaps a greater urgency or desire for playground upgrades than is actually felt by the wider community. This happens because the opinions of frequent park-goers are amplified over those who might not visit or care as deeply. It is crucial to identify and correct biases to ensure decisions made are truly reflective of broader public sentiment.

• Selection Bias: Happens when certain groups are more likely to be included in a survey than others.
• Non-response Bias: Occurs if certain parts of the population are less likely to respond, skewing results.
• Response Bias: When respondents answer questions untruthfully or misleadingly, potentially due to the survey settings or question wording.

Evaluating and addressing these biases can help in obtaining a clear and fair understanding of community needs.