Intro to Statistics with R: Introduction
Intro to Statistics with R: Introduction
Measures of variability
Intro to Statistics with R : Introduction
Measures of variability ●
Describe spread of scores in a distribution
●
Variance
●
Standard deviation
Intro to Statistics with R : Introduction
Standard Deviation ●
Σ(X) Mean = N 2 [Σ(X - M) ]
●
Variance =
●
Standard deviation = √Variance
N
Intro to Statistics with R: Introduction
Let's Practice!
Intro to Statistics with R: Introduction
Calculating variance in practice
Intro to Statistics with R : Introduction
Linsanity!
Intro to Statistics with R : Introduction
Jeremy Lin (10 games) Points per game
(X - M)
(X - M)2
28
5.3
28.09
26
3.3
10.89
10 27
-12.7 4.3
161.29 18.49
20
-2.7
7.29
38
15.3
234.09
23
0.3
0.09
28
5.3
28.09
25
2.3
5.29
2
-20.7
428.49
M = 227/10 = 22.7
M = 0/10 = 0
M = 922.1/10 = 92.21
Intro to Statistics with R : Introduction
Results ●
M = Mean = 22.7
●
2 SD = Variance = 92.21
●
SD = Standard Deviation = 9.6
Includes 2-point game, before he was a starter
Intro to Statistics with R : Introduction
Notation ●
M = Mean
●
SD = Standard Deviation
●
2 SD = Variance (also known as MS)
●
MS stands for Mean Squares
●
SS stands for Sum of Squares
Intro to Statistics with R: Introduction
Let’s Practice!
Intro to Statistics with R: Introduction
Quick summary
Intro to Statistics with R : Introduction
Summary Central tendency
● ●
Mean
●
Median
●
Mode Variability
● ●
Standard Deviation
●
Variance
Intro to Statistics with R : Introduction
Important formulas ●
Mean = M = (ΣX) / N
●
Variance ●
2 2 Descriptive: SD = [Σ(X - M) ] / N
●
2 2 Inferential: SD = [Σ(X - M) ] / (N – 1)
Intro to Statistics with R: Introduction
Congratulations!
Measures of variability
Intro to Statistics with R : Introduction
Measures of variability ●
Describe spread of scores in a distribution
●
Variance
●
Standard deviation
Intro to Statistics with R : Introduction
Standard Deviation ●
Σ(X) Mean = N 2 [Σ(X - M) ]
●
Variance =
●
Standard deviation = √Variance
N
Intro to Statistics with R: Introduction
Let's Practice!
Intro to Statistics with R: Introduction
Calculating variance in practice
Intro to Statistics with R : Introduction
Linsanity!
Intro to Statistics with R : Introduction
Jeremy Lin (10 games) Points per game
(X - M)
(X - M)2
28
5.3
28.09
26
3.3
10.89
10 27
-12.7 4.3
161.29 18.49
20
-2.7
7.29
38
15.3
234.09
23
0.3
0.09
28
5.3
28.09
25
2.3
5.29
2
-20.7
428.49
M = 227/10 = 22.7
M = 0/10 = 0
M = 922.1/10 = 92.21
Intro to Statistics with R : Introduction
Results ●
M = Mean = 22.7
●
2 SD = Variance = 92.21
●
SD = Standard Deviation = 9.6
Includes 2-point game, before he was a starter
Intro to Statistics with R : Introduction
Notation ●
M = Mean
●
SD = Standard Deviation
●
2 SD = Variance (also known as MS)
●
MS stands for Mean Squares
●
SS stands for Sum of Squares
Intro to Statistics with R: Introduction
Let’s Practice!
Intro to Statistics with R: Introduction
Quick summary
Intro to Statistics with R : Introduction
Summary Central tendency
● ●
Mean
●
Median
●
Mode Variability
● ●
Standard Deviation
●
Variance
Intro to Statistics with R : Introduction
Important formulas ●
Mean = M = (ΣX) / N
●
Variance ●
2 2 Descriptive: SD = [Σ(X - M) ] / N
●
2 2 Inferential: SD = [Σ(X - M) ] / (N – 1)
Intro to Statistics with R: Introduction
Congratulations!
