J-score*

What is J-score?

Welcome to J-score! This website provides an summarized overview of the Normal Distribution and its subtopics, such as the Z-Score, probability with the Normal Distribution, and the R-Score. The R-Score is especially interesting since it is widely used in CEGEPs in Quebec to assess academic performance, and it is difficult for students to calculate. Fortunately, we have built tools that can accurately predict the probability of getting into a university program based on a student's current R-Score, along with an R-Score calculator!

Section 1: Some definitions!

Variance

A variance shows how far values spread from the mean, which is the average of a sample set. The variance is found by averaging squared differences from that mean. It's squared to make large deviations count more, highlighting datasets with wide spread.

Image of variance formula

Standard deviation

Image of standard deviation formula

The standard deviation is the most common measure of data variability. A small standard deviation means that the data points are clustered near the mean, showing a low variability. A large standard deviation means that the data is widely spread out. The empirical rule states that 68% of all data falls within a standard deviation of the mean.

Standard Normal Distribution

A standard normal distribution is a bell shape chart where most values cluster near the mean and fewer appear at the extremes. It's has a mean of 0 and a standard deviation of 1. A useful rule of thumb is the 68-95-99.7 rule: about 68% of values lie within one standard deviation of the mean, ~95% within two, and ~99.7% within three. This is assuming that the data are approximately near the mean. This lets use probabilities and compare results fairly across classes or tests.

Image of the standard normal distribution graph

Section 2: Z-Score (Standard Score)

The Z-Score measures how many standard deviations a chosen data point is above or below the mean.

The Z-Score allows us to compare data. By converting each data point to Z-Scores, we can see how far away each data point is located from the standard deviation. A positive Z-Score indicates that the chosen data is above the average and a negative means it is below.

Image of Z-Score formula

Section 3: Application in the Admissions Calculator

Graph of R-Score Probability

Our admissions calculator uses the Z-Score to calculate your chances of getting in to your dream college. We use the properties of a normal distribution, assuming that the the mean is 0.025 below the historical cut-off score and standard deviation is 0.75. Once you input your R-Score, our calculator standardizes it into a Z-Score. This Z-Score is then mapped to a percentile on the standard cure, providing you with a statistically approximated probability.

Example: In the graph, we used an example R-Score of 30.025 as the mean. If a student has an R-Score of 30.75, this is approximately one standard deviation above the mean. In a normal distribution, one standard deviation above the mean corresponds to 34.1% of the area. Because he is already above the mean, we add the 50% below the mean. This means the student is around the 84th percentile, so he has roughly an 84.1% chance of being above the required R-Score of 30.025.

Calculate Your Probability!

Section 4: R-Score

The R-Score is equal to:

R-Score formula

Here's what every variable means:

Z = the Z-Score for a course: IFGZ or ISGZ = l'indicateur de la force du groupe (indicator of the strength of the group) IDGZ = l'indicateur de la dispersion du groupe (indicator of the dispersity of the group) The two mysterious 5 constants

Why is it difficult to calculate an accurate R-Score?

The IFGZ and IDGZ are the only constants that are difficult to find without the prior data from High School. This data is protected by the Ministry of Education and the Bureau de coopération interuniversitaire (BCI). Therefore, these variables vary tremendously. As students, we cannot get these exact values and without those exact numbers, you can only estimate your R-Score.

How do we estimate your R-Score?

Calculate your R-score!

Graph of R-Scores of Dawson Science Students