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Interpreting a trend line

Sal interprets a trend line that shows the relationship between study time and math test score for Shira. Created by Sal Khan.

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• Can someone please explain what bivariate data is ?
• Same as above, but maybe a better way to understand vocab:
bi = 2
variate = variables
• This isn't exactly a question about the video, but is it possible to determine the line of best fit without a graph? If you have several points, and no graph, how would you determine the equation of the line of best fit?
Thanks.
• If you had no graph, then you wouldn't be able to calculate the slope. So, I'd say your best bet is to eyeball it, and try to keep the line in the center of the data trend. If you're answering a question on paper, then definitely use a ruler. If you really wanted to calculate slope, then you could make a graph and plot the points on the graph. I find that calculating the slope is really helpful when determining the line.
• I am not sure if there is an easier way to go about this but there has to be some sort of formula. It is hard eyeballing the line and then it is even more difficult trying to measure a line on a computer screen........
• when would i use a scatter plot? Why would i need to know the trend?
• Why is it important that for a best-fit line be drawn with an equal number of data points above and below the line?
• It isn't actually too important. It usually just turns out that way because it's the average line of the data points make.
• At , what does Sal mean?
• if the first statement were true, at x=0 (did not study), you would have seen a score of 15 --> (0,15) -> but there is no datapoint to indicate this, so this first statement is false/incorrect.
• Does line of best fit have to be exact? The line of best fit can also be used to find slope, so if you don't place the line of best fit perfectly, the actual slope maybe a bit off. How can I fix this kind of problem?
• Hi moderators,

i noticed that the content in this video is repeated in another video in the same module "interpreting slope of a line". the content is same in both the videos.
• In the video, Sal mentions that the slope of the line on the graph, which is 15, means that for every hour a student studies, there is a 15 point improvement on their test.
Does this work every time? Is it always going to be increasing on the x-axis by one? Or does it just depend on the graph you are working with?
Also, to find the slope and analyze what it is saying (just like the question Sal is solving in the video) do you just start at a "whole number point" on the line and then travel vertically until you reach another "whole number" in order to see the change? For example, Sal first begins at point (0.5, 45) and travels horizontally to point (1.5, 60) to find the meaning in the change of slope.

Well, that was a mouthful! Thanks for anyone who helps, and I hope this helped other viewers too! :)