 Inferential Statistics I at Leuphana Universität | Flashcards & Summaries

# Lernmaterialien für Inferential Statistics I an der Leuphana Universität

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TESTE DEIN WISSEN

What is true for a t-test for independent samples and a t-test for the point-biserial correlation?

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TESTE DEIN WISSEN

The t-test for independent samples and the t-test for the point-biserial correlation is the same!

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TESTE DEIN WISSEN

How can we transform delta into f?

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TESTE DEIN WISSEN

d = 2f

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TESTE DEIN WISSEN

The result of a t-test is non-significant. We haven't run a a-priori sample size analysis. Under which conditions can we interpret this result?

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TESTE DEIN WISSEN

we can only interpret a non-significant result when the test power is sufficiently large (and beta error is sufficently small). If the result was signfiicant, we could interpret it right away and calculate effect size.

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TESTE DEIN WISSEN

What is the t-test and what is its function and how is it calculated?

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TESTE DEIN WISSEN
• standardised difference between two samples
• t-test compares two means (means between two groups) and calculates whether they are significantly different
• we divide difference in means by standard error// pooled standard deviation and get t = -4.314
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TESTE DEIN WISSEN

what is the R code for a one-sample test with a test-value of 1.7?

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TESTE DEIN WISSEN

t.test(dat\$abino, mu = 1.7)

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TESTE DEIN WISSEN

When do we take the Welsh T-Test?

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TESTE DEIN WISSEN

when the variances of the two groups are not equal

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TESTE DEIN WISSEN

What are 3 assumptions / requirements of the NHST?

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TESTE DEIN WISSEN
1. The variable x is interval scaled
2. x follows a normal distribution in the population
3. Null hypothesis: the samples are from a population with identical means and identical variance (= variance homogeneity)
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TESTE DEIN WISSEN

What is the function of the Levene's test?

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TESTE DEIN WISSEN
1. tests for variance homogeneity with an F-test (H0: variance homogeneity is given)
2. if F-test is significant, there is no variance homogeneity --> Null hypothesis is not true
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TESTE DEIN WISSEN

What does the null hypothesis assume?

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TESTE DEIN WISSEN
• an observed difference in means is random / due to a sampling error
• the experimental manipulation does not have a systematic influence
• The mean for the distribution of differences of means “Stichprobenkennwerte-Verteilung”) – given the null hypothesis – will have the value zero — irrespective of the mean value of the population the means were drawn from

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TESTE DEIN WISSEN

What is the empirical alpha probability?

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TESTE DEIN WISSEN

the probability to find the observed difference in means or any larger difference in means under the H0-t-distribution

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TESTE DEIN WISSEN

When is the result of a test significant?

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TESTE DEIN WISSEN

when the empirical alpha-error is smaller than the significance level determined prior to running the test (mostly, significance level is 0.05). If a result is significant, we discard the null hypothesis and decide in favor of the alternative hypothesis H1

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TESTE DEIN WISSEN

What is the problem with sample size and significance that can occur for NHST?

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TESTE DEIN WISSEN

only the increase in sample size makes an effect significant with the SD of the difference in means and estimated population variance staying constant!

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Q:

What is true for a t-test for independent samples and a t-test for the point-biserial correlation?

A:

The t-test for independent samples and the t-test for the point-biserial correlation is the same!

Q:

How can we transform delta into f?

A:

d = 2f

Q:

The result of a t-test is non-significant. We haven't run a a-priori sample size analysis. Under which conditions can we interpret this result?

A:

we can only interpret a non-significant result when the test power is sufficiently large (and beta error is sufficently small). If the result was signfiicant, we could interpret it right away and calculate effect size.

Q:

What is the t-test and what is its function and how is it calculated?

A:
• standardised difference between two samples
• t-test compares two means (means between two groups) and calculates whether they are significantly different
• we divide difference in means by standard error// pooled standard deviation and get t = -4.314
Q:

what is the R code for a one-sample test with a test-value of 1.7?

A:

t.test(dat\$abino, mu = 1.7)

Q:

When do we take the Welsh T-Test?

A:

when the variances of the two groups are not equal

Q:

What are 3 assumptions / requirements of the NHST?

A:
1. The variable x is interval scaled
2. x follows a normal distribution in the population
3. Null hypothesis: the samples are from a population with identical means and identical variance (= variance homogeneity)
Q:

What is the function of the Levene's test?

A:
1. tests for variance homogeneity with an F-test (H0: variance homogeneity is given)
2. if F-test is significant, there is no variance homogeneity --> Null hypothesis is not true
Q:

What does the null hypothesis assume?

A:
• an observed difference in means is random / due to a sampling error
• the experimental manipulation does not have a systematic influence
• The mean for the distribution of differences of means “Stichprobenkennwerte-Verteilung”) – given the null hypothesis – will have the value zero — irrespective of the mean value of the population the means were drawn from

Q:

What is the empirical alpha probability?

A:

the probability to find the observed difference in means or any larger difference in means under the H0-t-distribution

Q:

When is the result of a test significant?

A:

when the empirical alpha-error is smaller than the significance level determined prior to running the test (mostly, significance level is 0.05). If a result is significant, we discard the null hypothesis and decide in favor of the alternative hypothesis H1

Q:

What is the problem with sample size and significance that can occur for NHST?

A:

only the increase in sample size makes an effect significant with the SD of the difference in means and estimated population variance staying constant! ### Erstelle und finde Lernmaterialien auf StudySmarter.

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