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Overview of basic concepts in Statistics and Probability - SAMSI

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A 95 percent confidence <strong>in</strong>terval for µ<br />

<strong>Overview</strong> <strong>of</strong><br />

<strong>basic</strong> <strong>concepts</strong><br />

<strong>in</strong> <strong>Statistics</strong><br />

<strong>and</strong><br />

<strong>Probability</strong><br />

Avanti<br />

Athreya<br />

Prelim<strong>in</strong>aries<br />

Important<br />

distributions,<br />

scal<strong>in</strong>g laws,<br />

<strong>and</strong> the CLT<br />

Parametric<br />

estimation <strong>and</strong><br />

hypothesis<br />

test<strong>in</strong>g<br />

So we know<br />

P<br />

(<br />

Thus<br />

(∑ n<br />

1<br />

P<br />

X i<br />

n<br />

−1.96 <<br />

∑ n<br />

1 X )<br />

i<br />

n<br />

− µ<br />

σ/ √ < 1.96 = .95<br />

n<br />

− 1.96σ √ n<br />

< µ < 1.96σ √ n<br />

+<br />

<strong>and</strong> the r<strong>and</strong>om <strong>in</strong>terval<br />

(∑ n<br />

1 X i<br />

− 1.96σ ∑ n<br />

√<br />

1<br />

,<br />

X i<br />

n n n<br />

∑ n<br />

1 X )<br />

i<br />

= 0.95<br />

n<br />

+ 1.96σ )<br />

√ n<br />

is called a 95 percent confidence <strong>in</strong>terval for µ.<br />

In a large number <strong>of</strong> draws <strong>of</strong> the r<strong>and</strong>om sample, this <strong>in</strong>terval<br />

will conta<strong>in</strong> the true value µ about 95 out <strong>of</strong> 100 times.

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