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Data Analysis Data Analysis Basics Getting to Know Your Data Analyzing Data Spread

Max Erlich
Max Erlich
3,581 Points
Posted by Max Erlich
Max Erlich
3,581 Points

Where do these numbers come from?

0:45 sends into the video, I don’t understand where 70.21 and 198.79 come from and at 1:19 I don’t understand why they shrink to 97 and 131. Are these numbers arbitrary?

2 Answers

Steven Parker
Steven Parker
231,261 Points
Steven Parker
Steven Parker
231,261 Points

Those numbers are based on the sample bowling score data being analyzed. The middle value is the average of the scores, and the upper and lower values are the mean with the calculated standard deviation added and subtracted from it.

As the video moves on, the top score in the sample data set is changed from 300 to 135 and the mean and standard deviation are recalculated and the graph is updated with those new values.

lisablue
lisablue
1,392 Points
lisablue
lisablue
1,392 Points

At :45, the standard deviation was 64.29 .. so you take the average, and add 64.29 to get the right border of the range, and subtract 64.29 from the average to get the left border of the range of 1 standard deviation. The data at 1:19, is if instead of a perfect game (300), you change it to 135, then the average would change, and the subsequent standard deviations left and right would change and get smaller. To continue on with that, you could draw a bell curve between the left and right range, and you would then conduct a t-test to determine if whatever point you are examining at the standard deviation is significant or not (at 95% confidence level, for example). but that's beyond the lesson he's teaching at the moment. But that's how you get the number.s. you take the average, and add/ subtract to get your deviation range. Hope that helps.