Session 2b Flashcards

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1
Q

Hypothesis Testing About a Single Mean - t-test purpose

A

Based on the sample mean (X) we test whether the population mean
(μ) is equal to some hypothesized value

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2
Q

Prior Requirements/Assumptions of t-test

A

The variable, X, in the population is normally distributed

The sample must be a simple random sample of the population (independence of observations)

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3
Q

A t-statistic is obtained by replacing the population standard deviation with the sample standard deviation, due to this replacement, the t-statistic does not follow the standard
normal distribution. Instead, it follows what

A

the t-distribution

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4
Q

The t distribution has what shape

A

Varies in shape according to the degrees of freedom, df = N − 1

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5
Q

The t distribution approaches a normal distribution as df (or sample size) becomes what

A

large

The distributions are quite close for df > 30.

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6
Q

The t distribution was discovered by William S. Gosset in 1908. Gosset was a statistician employed by the Guinness brewing company and he couldn’t publish under his own name. what is another name for the t distribution

A

students t distribution

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7
Q

Hypothesis Testing About Two Means - t-test

what is the purpose

A

To test whether two unknown population means (μ1 and μ2) are different from each other - based on their samples

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8
Q

for hypothesis testing aout 2 means (t-test), The two samples may be eitherwhat

A

independent or correlated

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9
Q

what are Independent samples also known as

A

Also known as “between-subjects” designs

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10
Q

Example: Each participant only goes through one of two conditions in an experiment
Mean preference scores for a brand between treatment (Ad) and control (No ad) groups of subjects
what is this an example of

A

independant samples

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11
Q

Correlated samples:

Also known as what

A

“dependent-subjects”, “paired-samples”, “repeated-measures”, and so on

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12
Q

Example: Each participant may go through both conditions in an experiment
Mean preference scores for a brand for before seeing an Ad and after seeing an Ad for the same subjects

what is this an example of

A

correlated samples

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13
Q

in independent sample t-tests, how are participants assigned

A

Participants are randomly assigned to one of two conditions:
Example: A marketing researcher wants to test the effect of a new ad on
consumers’ preference ratings

no ad – group one (control) – X1

ad – group 2 (treatment) – X2

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14
Q

Prior Requirements/Assumptions: for Independent Samples t-test

A

Both populations are normally distributed
The standard deviations (σ1 and σ2) of the populations are the same
– Homogeneity of variance (σ12 = σ2)

Each subject is independent
Simple random sample from population

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