1.5 - Statistical Tests 1

Question 1

normal distribution

Answer 1

mean and standard deviation independent of one another

Question 2

standard normal distribution

Answer 2

mean of 0and standard deviation of 1

Question 3

compare normal distributions to standard normal distribution calculation

Answer 3

Z = (Y - Y)
/S
Z = probability with which value lies in a range
Y = Y value
Y = mean
S = standard deviation

Question 4

null hypothesis

Answer 4

statement about world that can be falsified; no signal

Question 5

alternative hypothesis

Answer 5

signal (often research hypothesis)

Question 6

P-valueVariables that determine what statistical test to do? (5)

Answer 6

1. what type of response variable
2. what type of explanatory variable
3. interested in differences or trends/ relationships
4. paired or independent sample
5. distribution

Question 7

different types of response variable (4)

Answer 7

1. continuous
2. discrete/count
3. proportion
4. binary

Question 8

different types of explanatory variables (5)

Answer 8

1. continuous
2. discrete/count
3. proportion
4. binary
5. categorical

Question 9

different types of distribution (2)

Answer 9

1. normal
2. non-normal

Question 10

paired sample

Answer 10

first and second measurement of the same individual are not independent of each other

Question 11

normal distribution (6)

Answer 11

1. parametric tests
2. powerful, easy to interpret
3. use means
4. require data (or residuals) to be normally distributed
5. often require similar variance in groups
6. can be used to answer complicated questions

Question 12

non-normal distribution (6)

Answer 12

1. non-parametric tests
2. less powerful, more conservative
3. use medians (data usually ranked before test)
4. usually no assumptions about distribution of data
5. robust
6. often restrictive, cannot answer more complex Qs

Question 13

how to check for normal distribution (2)

Answer 13

1. graphically (does it look normal)
2. formal tests (shapiro-wilk test)

Question 14

shapiro-wilk test in R

Answer 14

shapiro.test(variable name)
H0 = no deviation from normal distribution
P = < 0.05 = reject H0, >0.05 = dont reject (normal)

Question 15

chi-squared response variable/explanatory variable (2)

Answer 15

1. response variable = count (observations)
2. explanatory variable = categorical

Question 16

chi-squared

Answer 16

look at one note