Summa Week 14

Question 1

True or false?: Do we use nonparametric procedures when normality cannot be assumed?

Answer 1

true

Question 2

True or false?: Do we use nonparametric procedures when data can be transformed to normality

Answer 2

false. we use it typically when data CANNOT be transformed to normality

Question 3

True or false?: Do we use nonparametric procedures when methods based on non-normal distributions are not available or appropriate

Answer 3

true

Question 4

True or false?: Do we use nonparametric procedures when there is a sufficient sample size to assess the form of the distribution

Answer 4

false. we use it typically when there is NOT a sufficient sample size to assess the form of the distribution

Question 5

True or false? The precise definition of nonparametric statistics does not vary among statistics textbooks

Answer 5

false. although not completely, there are differences

Question 6

True or false? Nonparametric statistics = distribution-free statistics

Answer 6

false. they are different yes mistakenly used interchangeably

Question 7

What are distribution-free tests?

Answer 7

statistical tests that don’t rely on assumptions about the prob distribution of the sample population

e.g. do not require normally-distributed data

Question 8

What are nonparametric procedures?

Answer 8

inferential statistics that do not rely on population estimation of which the experiment is sampled from

Question 9

What are rank stats or rank tests?

Answer 9

ordinal data from lowest to highest and assigning them integer values from 1 to the sample size

Question 10

How do you resolve tied values in rank stats?

Answer 10

assigning them the average of the ranks if there were no ties

e.g. 17, 19, 19, 25, 28 becomes 1, 2.5, 2.5 (both share 2nd and 3rd place, with (2+3)/2 = 2.5)

Question 11

What are assumptions of parametric methods?

Answer 11

generally assumes a random sample from a normal distribution

Question 12

What are assumtions of nonparametric methods?

Answer 12

few assumptions about the pop distribution

Question 13

What is in comparison in regards to the DV for nonparametric methods?

Answer 13

may be measured on categorical, ordinal, interval or ratio scales

Question 14

What is in comparison in regards to the DV for parametric methods?

Answer 14

measured on interval or ratio scale, DV

Question 15

What is comparison in regards to sample sizes for nonparametric methods?

Answer 15

can be small

Question 16

What is in comparison for samples sizes in parametric methods?

Answer 16

often requires large sample sizes (e.g., n > 30 for the central limit theorem, or pairs of 15, etc.) to appeal to normality

Question 17

What is the equivalent non-parametric test for an independent samples t-test?

Answer 17

a median test or a rank sum test (compares 2 independent samples)

Question 18

What is the equivalent non-parametric test for a paired samples t-test?

Answer 18

a Sign tests or a Wilcoxon test (2 matched/related-pairs samples)

Question 19

What is the equivalent non-parametric test for a one-way ANOVA?

Answer 19

a Kruskal-Wallis test (compares more than 2 independent samples)

Question 20

What is the equivalent non-parametric test for a two-way ANOVA?

Answer 20

a Friedman test

Question 21

What is the equivalent non-parametric test for a Pearson’s correlation?

Answer 21

a Spearman’s Rank Correlation

Question 22

What is the equivalent parametric test for a distribution comparison?

Answer 22

there isn’t one. There is only the non-parametric test of Kolmogorov-Smirnov (damn those Russians)

Question 23

If you have a tiny sample size, what could you do to estimate the population?

Answer 23

resample by bootstrapping

Question 24

What is bootstrapping?

Answer 24

a stat method for estimating the sampling distribution of an estimator by sampling with replacement from the original sample

Question 25

What is most often the purpose of bootstrapping?

Answer 25

deriving robust estimates of standard errors and CIs of a population parameter like a mean

Question 26

Fill in the blanks: _______ is a stat method for estimating the _____________ of an estimator by sampling with _______ from the original sample

Answer 26

bootstrapping
sampling distribution
replacement

Question 27

Fill in the blanks: the purpose of ________ is to derive ___________ of ____________ and confidence intervals of a ________ ________ like a mean

Answer 27

bootstrapping
robust estimates
standard errors
population parameter

Question 28

Is this an advantage of nonparametric procedures? It has higher power

Answer 28

hell naw. this is the reason to do parametric methods!

Question 29

Is this an advantage of nonparametric procedures? it relies on a few assumptions about the distribution of the sampled population

Answer 29

true. it’s less picky than parametric methods

Question 30

Is this an advantage of nonparametric procedures? it gets a quick answer with little calculation

Answer 30

true. the Sign test is eeeeeeeeasy

Question 31

Is this an advantage of nonparametric procedures? it uses a random sample from a larger population when it isn’t available

Answer 31

yep, i.e. bootstrapping

Question 32

Is this an advantage of nonparametric procedures? is can use a small sample size

Answer 32

hell yeah

Question 33

Nonparametric methods are most appropriate when the sample sizes are ______

Answer 33

small

Question 34

When the dataset is large (i.e. n > 100), it makes little sense to use nonparametric stats because

Answer 34

when the samples are large, the sample means will follow the normal distribution even if the respective variable is not normally distributed in the population

Question 35

Is this a disadvantage of nonparametric procedures? it doesn’t describe parameters and becomes difficult to make qualitative statements about the actual difference between populations

Answer 35

trick question. it’s false because although they don’t describe parameters, they make it difficult to make QUANTITATIVE statements

Question 36

Is this a disadvantage of nonparametric procedures? it throws away information

Answer 36

true, e.g. the sign test

Question 37

Is this a disadvantage of nonparametric procedures? it has less power than parametric procedures

Answer 37

yep

Question 38

Each nonparametric procedure has its peculiar sensitivities and blind spots such as: the Kolmogorov-Smirnov 3-sample test is sensitive to differences in the location of distributions as well as is greatly affected by differences in shapes

Answer 38

false. although the statement is true, the Kolmogorov-Smirnov is a 2-SAMPLE test, not a 3-sample one

Question 39

True or false: the Wilcoxon matched pairs test assumes that one can rank order the magnitude of differences in matched observations in a meaningful manner.

Answer 39

true

Question 40

If the rank order of magnitude of differences in matched observations is not possible, what should you use?

Answer 40

a Sign test

Question 41

True or false: it is always advisable to run at least 2 nonparametric tests

Answer 41

true. should discrepancies in the results occur contigent upon which test is used, one should try to understand why some tests give different results