Grouped continuous data (AQA GCSE Statistics): Flashcards
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What is the standard deviation formula for grouped data?
What is the standard deviation formula for grouped data?
Standard deviation = √(Σfx²/Σf - (Σfx/Σf)²)
Why do we use mid-points in grouped data calculations?
Why do we use mid-points in grouped data calculations?
Mid-points represent typical values for class intervals.
How do you calculate fD for a class interval?
How do you calculate fD for a class interval?
fD = Frequency × Mid-point of the class interval.
What does Σf represent in statistics calculations?
What does Σf represent in statistics calculations?
Σf is the sum of all frequencies in a dataset.
Calculate the mean from ΣfD = 300 and Σf = 60.
Calculate the mean from ΣfD = 300 and Σf = 60.
Mean = 300/60 = 5.
What is the first step in calculating standard deviation?
What is the first step in calculating standard deviation?
Calculate the mean of the data set.
Why is the standard deviation an estimate for grouped data?
Why is the standard deviation an estimate for grouped data?
We assume all values are at the mid-point of intervals.
Calculate the mean of D² if ΣfD² = 2000 and Σf = 50.
Calculate the mean of D² if ΣfD² = 2000 and Σf = 50.
Mean of D² = 2000 / 50 = 40.
What should you do after summing f, fD, and fD²?
What should you do after summing f, fD, and fD²?
Calculate the mean and then apply the SD formula.
How does interval width affect standard deviation accuracy?
How does interval width affect standard deviation accuracy?
Narrow intervals yield more accurate estimates.