4.6 WS Std Dev 1 Name # 8 Step Process Date

[Pages:1]4.6 WS ? Std Dev 1 8 Step Process

Name

_________________ # __ Date _________

Standard deviation tells us

How far, on average Any data point is from the mean

Standard Deviation is the Average Distance from the Mean.

Smaller standard deviation ? scores are closer, on average, to the mean Larger standard deviation ? scores are further away, on average, from the mean

Follow the steps below to calculate the standard deviation.\ Step 1: Order Data from lowest to highest

Step 2:

Mean

y

Step 3: Step 4: Step 5: Step 6:

(Difference of the Mean)

(Difference of the Mean)2 (Difference of the Mean)2

yi y

2

yi y

n

(yi y)2

i1

Subtract each score from the mean

Square each number from Step 2

Sum (Difference of the Mean)2

Count

n

# of items in data set

Step 7: Step 8: Step 9:

Degrees of freedom

(n ? 1)

Variance

s2

Standard Deviation

s

2

s2

yi y

n 1

2

s

yi y

n 1

Okay, technically 9 Steps, but step 6 is a do over.

For each practice problem use the 8 step process and find:

A) Mean

B) Degrees of Freedom

C) Variance

D) Standard Deviation

Practice Problem #1: Number of baskets scored per game: 8, 4, 6, 6, 7, 7, 9, 4, 8, 5.

Practice Problem #2 Test scores: 85, 100, 92, 96, 87, 94, 75

Practice Problem #3 Quiz Scores: 22, 99, 102, 33, 57, 75, 100, 81, 62, 29

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