Week 2 descriptives

Question 1

Nominal data

Answer 1

Categorical data eg gender

Question 2

Ordinal data

Answer 2

Orders people, objects or events along some continuum. No information is given about the differences between the points in the scale

Question 3

Interval scales

Answer 3

Equal intervals between objects represent equal differences.

No absolute/true zero point

Cannot make ratio comparisons

Eg time, temp and IQ

Question 4

What does no true zero point mean

Answer 4

It’s not nothing.

E.g 0 Celsius is not as lack of temperature, it is a degree and means something

Question 5

Ratio scales

Answer 5

True zero point

Higher level of measurement - more detailed

Question 6

What is the goal of Descriptive statistics

Answer 6

Characterize a numerical dataset efficiently

Condense meaningful information

Minimize the inevitable error involved during condensation

Question 7

What is the goal of inferential statistics

Answer 7

infer the characteristics of the whole population are from a sample

Going beyond the information given to make likely assertions rather than certain ones

Sample statistics (English letters) are used to estimate population parameters ( Greek letters)

Key ideas: theoretical sampling distributions composed of innumerable random samples

key indices - p-value and confidence intervals

Question 8

measures of central tendency

Answer 8

mean, median and mode

Question 9

mean

Answer 9

average - add all and divide by how many present

Question 10

cons of using the mean

Answer 10

inaccurate description and extreme scores influence mean

Question 11

what does a histogram tell us

Answer 11

if the data is symmetrical and if the mean is appropriate to describe the sample

Question 12

median

Answer 12

the score in the middle when are scores are arranged from smallest to largest

Question 13

pro of using median

Answer 13

not affected by extreme scores

more accurate representation of data

Question 14

mode

Answer 14

the most frequent score

Question 15

what central tendency can nominal data only use

Answer 15

mode

Question 16

what does measure of variability describe

Answer 16

the degree to which values vary

Question 17

what are the measures of variability

Answer 17

range, interquartile range, variance and SD

Question 18

range

Answer 18

difference between max and min scores

Question 19

pros of using range

Answer 19

straightforward to calculate and easy to interpret

Question 20

cons of using range

Answer 20

unstable across different samples

easily distorted by outliers

Question 21

what does interquartile range use

Answer 21

percentiles

Question 22

what are percentiles

Answer 22

cut off point that divides the data into percentage chunks

Question 23

variance

Answer 23

a measure of how much the scores vary in terms of distance from the mean

the average of each scores squared deviation from the mean score

Question 24

when do you use population formula for variance

Answer 24

when you have a whole population and don’t want to generalize scores

Question 25

when do you use sample variance formula

Answer 25

when you want to estimate variance for population and generalize scores

Question 26

standard deviation

Answer 26

the square root of the average of each scores squared deviation of the mean score = the square root of variance

bigger value - more spread out