Given a set of data pairs, how would you decide whether to use interpolation or extrapolation to find a certain value?

use interpolation when the data falls within the range given by the model (when it says "based on data from such and such to such and such" or "this data applies to years x to y" when the year or time you're studying falls outside this range then you are using extrapolation

also, if you have a chart the x values in the chart represent the data range used for interpolation while anything lower than the min x value will be extrapolation and any term higher than the max x value will be extrapolation.

To decide whether to use interpolation or extrapolation to find a certain value from a set of data pairs, you need to consider the limits of the data range and the purpose of your analysis.

Interpolation is used when you want to estimate a value within the range of the data. It involves making predictions or estimating values based on existing data points. Interpolation assumes that the relationship between the data points is continuous and can be extrapolated within the given range. It is typically more accurate than extrapolation because it utilizes existing data trends.

Extrapolation, on the other hand, is used when you want to estimate a value outside the range of the data. It involves extending the existing data trends or patterns beyond the given range. Extrapolation assumes that the relationship between the data points continues beyond the observed range. However, extrapolation can be less reliable than interpolation since it relies on making assumptions about the data trends without concrete evidence.

To decide whether to use interpolation or extrapolation, consider the following factors:

1. Data Range: Check if the value you are trying to find falls within the range of the existing data points. If it does, then interpolation is appropriate. If it falls outside the range, then extrapolation would be necessary.

2. Data Patterns: Examine the trends and patterns in the existing data set. If there is a clear and well-defined trend, it may be more reasonable to use interpolation. If the pattern is inconsistent or shows significant variability, extrapolation may yield less reliable results.

3. Purpose: Consider the purpose of your analysis. If you need precise and accurate estimates, interpolation is generally preferred since it utilizes the existing data. However, if the degree of accuracy is less critical, and you need a rough estimate or a general trend, extrapolation can be considered.

It is important to note that extrapolation carries a higher risk of generating inaccurate results, so caution should be exercised if choosing this method. Whenever possible, it is advisable to have more data points in the range of interest to increase the reliability of both interpolation and extrapolation.