Régression Linéaire

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Questions and Answers

Un chercheur effectue une régression linéaire et obtient un coefficient de détermination ($R^2$) de 0,85. Qu'est-ce que cela indique sur la relation entre les variables ?

  • Il existe une forte relation non linéaire entre les variables.
  • 85 % de la variance de la variable dépendante est expliquée par la variable indépendante. (correct)
  • 85 % de la variance de la variable indépendante est expliquée par la variable dépendante.
  • Il n'y a pas de relation significative entre les variables.

Quel terme décrit le mieux une situation où un modèle de régression est excellent pour prédire les données utilisées pour l'entraîner, mais médiocre pour prédire de nouvelles données ?

  • Multicolinéarité
  • Hétéroscédasticité
  • Surajustement (correct)
  • Sous-ajustement

Dans l'analyse de régression, qu'indique une valeur p inférieure au niveau de signification (alpha) ?

  • La taille de l'échantillon est trop petite.
  • L'hypothèse nulle est vraie.
  • Le coefficient de régression est statistiquement non significatif.
  • Le coefficient de régression est statistiquement significatif. (correct)

Quel est l'impact de l'augmentation de la taille de l'échantillon sur la puissance d'un test statistique lors d'une régression linéaire ?

<p>Augmente la puissance. (B)</p> Signup and view all the answers

Dans une régression linéaire multiple, comment la multicolinéarité affecte-t-elle les coefficients des variables indépendantes ?

<p>Cela entraîne des estimations de coefficients instables et difficiles à interpréter. (D)</p> Signup and view all the answers

How does a pink substance differ from a green substance if the pink substance has weaker intermolecular attractions?

<p>The pink substance is more likely to be a gas at room temperature compared to the green substance. (A)</p> Signup and view all the answers

A scientist observes that a pink substance easily changes its shape when poured into a container, while a green substance retains its shape. Which best explains this?

<p>The pink substance has weaker intermolecular attractions, allowing its molecules to slide past each other more easily. (B)</p> Signup and view all the answers

Consider two substances: a pink one and a green one. The pink substance evaporates much faster at room temperature. What accounts for this difference?

<p>Stronger intermolecular attractions in the green substance. (B)</p> Signup and view all the answers

Imagine a pink substance expands significantly more than a green substance when heated. Which of the following conclusions is most likely true?

<p>The pink substance has weaker intermolecular attractions compared to the green substance. (A)</p> Signup and view all the answers

When comparing a pink and a green substance, it's observed that the pink substance has a lower boiling point. How do their intermolecular attractions likely differ?

<p>The pink substance has weaker intermolecular attractions, requiring less energy to change state. (D)</p> Signup and view all the answers

Flashcards

Intermolecular Attraction

The force that holds molecules together.

State of Matter and Attraction

Substances with stronger attractions between molecules are more likely to be solid or liquid at room temperature.

Molecular Movement & Energy

More energetic molecules overcome attractive forces, leading to changes in state.

Liquid State

A substance where molecules move around each other, has moderate intermolecular forces, it exists as a liquid.

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Solid State

A substance where molecules move in place, has very strong intermolecular forces, it exists as a solid.

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Study Notes

  • Option A proposes that the pink substance has a stronger attraction between its molecules compared to the green substance, allowing its molecules to move around each other.
  • Option B suggests the pink substance has a weaker attraction between its molecules than the green substance, causing its molecules to move away from each other.
  • Option C posits the pink substance has a stronger attraction between its molecules compared to the green substance, leading its molecules to move away from each other.
  • Option D states the pink substance has a weaker attraction between its molecules than the green substance, resulting in its molecules moving in place.

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