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The following summary table shows the number of space launches in the US by the type of launching agency and the outcome of the launch (success or failure). (a) What variables were collected on each launch in order to create to the summary table above? (b) State whether each variable is numerical or categorical. If numerical, state whether it is continuous or discrete. If categorical, state whether it is ordinal or not. (c) Suppose we wanted to study how the success rate of launches vary between launching agencies and over time. In this analysis, which variable would be the response variable and which variable would be the explanatory variable?

Short Answer

Expert verified
Variables: Type of Agency, Launch Outcome, Timeframe; all are categorical. 'Launch Outcome' is response; 'Agency' and 'Timeframe' are explanatory.

Step by step solution

01

Identify the Variables

For part (a), determine the variables collected to form the summary table. Given the information, the variables likely include 'Type of Launching Agency', 'Launch Outcome', and potentially 'Date' or 'Timeframe of Launch'. These describe who conducted the launch and the result.
02

Determine Variable Types

For part (b), classify each variable identified previously. 'Type of Launching Agency' is categorical (not ordinal) since it's a group name. 'Launch Outcome' is also categorical (not ordinal) as it's a description (success/failure). 'Date' or 'Timeframe' would be categorical if it's just grouped as years or numbers representing dates/times (if numerical, discrete).
03

Identify Response and Explanatory Variables

For part (c), in studying how launch success varies, the 'Launch Outcome' is the response variable since its value (success/failure) changes based on other conditions. The explanatory variable is 'Type of Launching Agency', which might affect success rates. If 'Timeframe' is considered, it too may be an explanatory variable, showing variation over time.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Categorical Variables
In statistical analysis, categorical variables are those that represent distinct categories or groups. They are not numerical, meaning you cannot perform mathematical operations on them. Instead, they describe qualities or characteristics.
For example, in the context of space launches, the 'Type of Launching Agency' and 'Launch Outcome' are categorical variables. The 'Type of Launching Agency' distinguishes between different entities that orchestrated the launch, like NASA or private companies. As these are just groups without an inherent order—NASA is not naturally greater or less than another agency—this variable is **not ordinal**.
Similarly, 'Launch Outcome' classifies each launch into a 'success' or 'failure.' This distinction is not ordinal either because success is not a degree more than failure. It's more about result characteristics. Categorical variables help in understanding the basic demographic or group-related data in a dataset.
  • Non-numerical variables
  • Classify data into distinct groups
  • Can describe characteristics or outcomes
  • Useful for identifying descriptive patterns
Response and Explanatory Variables
Identifying response and explanatory variables is crucial in analyzing how different factors affect a certain outcome. In the case of space launches, the 'Launch Outcome' acts as the response variable. This makes sense because it "responds" to conditions provided by other variables, like the 'Type of Launching Agency.'
The response variable is essentially what you are trying to understand or predict. It changes as a result of variations in other variables.
On the other hand, the 'Type of Launching Agency' is an explanatory variable. An explanatory variable is something you tweak or observe to see how it affects the response variable. Changes in the launching agency could influence the results or effectiveness of a launch.
Additionally, 'Timeframe' might also serve as an explanatory variable if you're considering historical trends or changes over different periods. These types of analyses help in identifying cause-and-effect relationships.
  • Response variable: outcome varies with other factors
  • Explanatory variable: factor influencing outcome
  • Essential for establishing causal links
Numerical Variables
Numerical variables reflect quantitative data and come in two main types: continuous and discrete. In the given problem, potential numerical variables like 'Date' or 'Timeframe of Launch' could be considered. If they capture specific numbers, they are likely discrete.
Discrete numerical variables are countable. For instance, if you count the number of launches within a year, each count is distinct and separate, making it a discrete variable.
Continuous numerical variables differ as they can take any value within a range, including fractions. While the exercise does not specify continuous variables, it is essential to recognize that continuous variables exist and are useful for more detailed analyses.
  • Discrete: distinct, countable numbers
  • Continuous: any value within a range
  • Critical for performing mathematical analyses
  • Can provide depth in understanding trends or patterns

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