Lecture 2

Question 1

define scatterplot

Answer 1

uses multiple data points represented as dots on the graph to show the distribution of a variable and to find the line of best fit
- 2 scale variable
- #’s have meaning
- continuous, ratio scale

Question 2

define line graph

Answer 2

used to measure continuous variables
- line graphs show more groups and conditions
- see interactions effects between groups
- ratio scale

Question 3

define bar graph

Answer 3

used to compare one or more variables between different subjects

Question 4

define dot plot

Answer 4

used to show frequency distribution across a sample
- cluster boxes
- median lines
- outliers

Question 5

define mean

Answer 5

the arithmetic average of a group of scores
- avg of scores/# of scores
- conveys weight of distribution

Question 6

define median

Answer 6

the middle score of all the scores in a sample when all the scores are arranged in ascending order. If there is no single middle score, the median is the mean of the two middle scores
- test for outliers

Question 7

define mode

Answer 7

most common score in a sample
- test for outliers

Question 8

what is central tendency

Answer 8

• mean
• median
• mode

Question 9

trimmed means

Answer 9

Discard a portion of the data from each end
- robust statistics (strong sturctured)
Ex. 10%-20% trimmed mean = remove 10%-20% lowest and highest

Question 10

define variability

Answer 10

is a numerical way of describing how much spread there is in a distribution
- Measures of central tendency do not tell the whole story
- scattered or clustered

Question 11

define range

Answer 11

is a measure of variability calculated by subtracting the lowest score (the minimum) from the highest score (the maximum)

Question 12

define interquartile range (IQR)

Answer 12

is a measure of the distance between the first and third quartiles

Question 13

define first quartile (Q1)

Answer 13

marks the 25th percentile of a data set

Question 14

define the third quartile (Q3)

Answer 14

marks the 75th percentile of a data set

Question 15

define variance

Answer 15

the average of the squared deviations from the mean

Question 16

deviation

Answer 16

is the amount that a score in a sample differs from the mean of the sample
- deviation from the mean

Question 17

How to calculate standard deviation (SD)

Answer 17

1. calculate mean
2. subtract mean from each observation - deviation scores
3. square the deviation scores
4. add the squared deviation scores - sum of squares
5. divide the sum of squares by the number of observations - variance
6. take the square root of that value to get the SD

Question 18

standard deviation

Answer 18

the square root of the average of the squared deviations form the mean; it is the typical amount that each score varies, or deviates, from the mean

Question 19

visual displays of data are

Answer 19

descriptive stats that provide more info about data