Statistics 1

Question 1

What are the main 2 types of data?

Answer 1

Numerical and categorical

Question 2

What are the 2 types of numerical data

Answer 2

Continuous and discrete

Question 3

What are the types of categorical data

Answer 3

-2 groups only (binary/dichotomous)
-Several groups (nominal/ordinal - with order)

Question 4

What are the different distributions of data?

Answer 4

-Normal (bell shape)
-Negatively skewed
-Positively skewed

Question 5

How to calculate standard deviation?

Answer 5

-Calculate mean of values
-For each value, calculate the difference from the mean
-Square the individual differences from the mean and add them up
-Variance = the sum of squared individual differences / number of observations - 1
-SD = square root of variance

Question 6

How do you calculate reference range?

Answer 6

Mean +/- 1.96 x SD

Question 7

What does reference range tell you?

Answer 7

-Tells you the upper and lower limits of which 95% of the data fall into

Question 8

If data are normally distributed what % of all measurements fall within 1 SD of the mean

Answer 8

68%

Question 9

If data are normally distributed what % of all measurements fall within 2 SD of the mean

Answer 9

95%

Question 10

What is the standard error

Answer 10

-SE is the SD of sample estimates
-SE used when looking at variation of sample means
-SD used when looking at variation of data about the mean

Question 11

How does SE differ from SD

Answer 11

-SE has a smaller range

Question 12

How do you calculate SE

Answer 12

Question 13

Calculate the SE and 95% CI

Answer 13

SE = 4.4 / square root of 1500 = 0.11
95% CI:
Lower CI = 27.8 - (1.96 x 0.11) = 27.6
Upper CI = 27.8 + (1.96 x 0.11) = 28.0