IPA IP 2024 Question 14
A question IPA Japan published in 令和6年度 ITパスポート試験 公開問題 問14, translated into English. ITPEC is based on the same exams.
When the relationship between the sales volume of a certain product and the temperature can be approximated by a linear equation, which of the following is an appropriate method for estimating the sales volume of the product from a forecast temperature?
Explanation
Regression analysis — fit a line to past data of temperature and sales, then read off the sales for the forecast temperature.
Regression analysis expresses one variable (the dependent variable, here sales volume) as a function of others (the explanatory variables, here temperature). With one explanatory variable and a straight line, the past data give the equation y = ax + b, usually by the least-squares method; substituting the forecast temperature for x gives the estimated sales volume y. How well the line fits can be judged from the correlation coefficient.
Answer (a)
Why not others:
- •(b) — linear programming finds the values of variables that maximize or minimize a linear objective, such as profit, under linear constraints, such as limits on materials; it does not estimate one variable from another
- •(c) — the Delphi method forecasts by sending repeated anonymous questionnaires to experts and feeding back the results until their opinions converge
- •(d) — Pareto analysis sorts items by size and plots their cumulative share to find the few that matter most (ABC analysis)
Key rule: Estimating one quantity from another through a fitted equation is regression analysis; optimizing under constraints is linear programming; gathering expert opinion is the Delphi method.
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This question comes from the past questions IPA Japan publishes, translated into English by ITPEC Practice. ITPEC Practice is an independent study tool and is not affiliated with IPA or ITPEC. See the original paper (PDF) or Report an issue.