# OCR MEI Statistics 1

In a probability distribution vertical line chart (sticky graph), the lowest probabilities are in the tails. What do critical regions involve?
Critical regions involve finding the outcomes that make up the smallest probabilities.
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How do you pick critical regions?
You usually look for the bottom/top 5% (which can change) of probability--> 0.05. Use binomial tables.
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Finding out if an observation is in the critical region.
Find the most appropriate critical region. If the observation (i.e. x=2) is in the critical region, it is regarded as SIGNIFICANT.
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Formal Hypothesis Testing, null hypothesis. P=...
Null hypothesis = normal result, H_0. (This agrees with the statement made)
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Alternative hypothesis. P>/
H_1. (This disagrees with the original person's claim and instead supports a suspicion).
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Probability.
P=probability of "insert_statement/claim_here" happening.
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Use B(n,p). Significance level.
Usually 5% unless otherwise stated.
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After setting up hypothesis test:
Work out critical regions. Is the observed value in this critical region.
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Observed value isn't in critical region:
"Observed value" is not significant, accept H_0. There is not enough evidence to suggest that "suspicion".
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Observed value is in critical region:
"Observed value" is significant, accept H_1. There is enough evidence to support the statement that "suspicion".
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What do Formal Hypothesis Tests look for?
An increase (>) or decrease (
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Two-tailed tests, what are they for?
Sometimes we don't specify an increase or decrease, we just suspect something different (probability could be higher or lower).
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H_0: P=...; H_1: P not-equal-to...
We need a critical region in both tails and we need to split the significance level in half.
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## Other cards in this set

### Card 2

#### Front

How do you pick critical regions?

#### Back

You usually look for the bottom/top 5% (which can change) of probability--> 0.05. Use binomial tables.

### Card 3

#### Front

Finding out if an observation is in the critical region.

### Card 4

#### Front

Formal Hypothesis Testing, null hypothesis. P=...

### Card 5

#### Front

Alternative hypothesis. P>/