Lecture 2 content- descriptive statistics

Question 1

What is quantiative research

Answer 1

collect numerical data that is analysed using stats.

Question 2

How is quantitative data gathered

Answer 2

by collecting quantifiable information from surveys tasks and experiments.

Question 3

What is qualitative research

Answer 3

it is exploratory, we are gaining an understanding of underlying reasons

Question 4

what methods are used for qualative research

Answer 4

focus groups, interviews to understand concepts such as intentions and motivations

Question 5

how do we gain a representative sample

Answer 5

having larger samples and matching general characteristics of the population.

Question 6

What are inferential statistics

Answer 6

uses sample data and helps us make inferences about the populations by drawing conclusions that are beyond our data.

Question 7

What are descriptive statistics

Answer 7

describes our data in the sample not necessarily the population.Data refers to the observations of ppts scores on the variables. Descriptive statistics refers to the numbers that summarise the observed information.

Question 8

what is a between subjects design

Answer 8

• Sample is divided into groups and each group received one treatment and performs one task.

Question 9

evaluate between-subject designs

Answer 9

• Requires larger number of participants for higher statistical power.
• Shorter duration prevents effects of learning and fatigue.

Question 10

what is a within subjectsd design

Answer 10

• All ppts in the study receive every treatment and perform every task .

Question 11

evaluate a within-subjects design

Answer 11

• Good to use when number of resources or ppts are limited.

Question 12

what is an IV

Answer 12

the one that is changed

Question 13

what is a dv

Answer 13

can change as it is based on the IV . The outcome of the DV is dependent on the IV . It is what we measure.

Question 14

what is nominal data

Answer 14

catagorical

Question 15

what is ordinal data

Answer 15

ordered data with intervals that are not the same

Question 16

what is interval data

Answer 16

has equal intervals between values

Question 17

what is ratio data

Answer 17

same as interval but has an absolute zero

Question 18

What are measures of central tendency

Answer 18

describes a tupical value on a variable
mode
median
mean

Question 19

What is the mode

Answer 19

is the most common value which is mostly used for nominal data.

Question 20

why is the mode problematic

Answer 20

it ignores a lot of the information about the scores. Only focuses on one value.

Question 21

what is the median

Answer 21

is the central value when observations are ordered from low to high. Mostly used with ordinal level data or if it is skewed but only uses 1-2 data points.

Question 22

what is the mean

Answer 22

you add up all the scores and divide by the number of values. May be affected by extreme values

Question 23

What types of models are central tendency

Answer 23

they are statistical models . Modells are smaller simpler ersions of what we want to look at. Not particularly accurate

Question 24

Describe a normal distribution

Answer 24

bell-shaped and symmetrical. Majority of the values are in the middle as the mean, mode and median are close together

Question 25

described a skewed distribution

Answer 25

-Majority of scores are at one end of the curve, and the mean is no longer central. Extreme values affect the mean.

Question 26

from skewed data what it is it important to calculate

Answer 26

IQR or the trimmed mean i the data is skewed and interval and ratio - data by removing extreme scores on both sides of the distrubution. if the data is ordinal / interval or ratio- can use median and range.

Question 27

typically what is the percentage of trimmed

Answer 27

5

Question 28

what is the calculation for a trimmed mean

Answer 28

Percent required x number scores / 100= number of ppts to reduce in our sample.

Question 29

what is the range

Answer 29

difference between the highest and lowest value. The range is strongly affected by extreme values because it takes the highest and lowest value

Question 30

what is the interquartile range

Answer 30

- similar method to trimmed mean. Range of the middle 50 percent scores. Remove the upper and lower 25 percent and compute the range

Question 31

equation for interquartile range

Answer 31

percentage required (25percent) x no scores/ 100.

Question 32

what is variance

Answer 32

the averaged squared deviation of scores from the mean

Question 33

what is the equation for variance

Answer 33

(∑(x-x ̅) ^2 /(n-1) x i ​ = each individual data point in the sample x ˉ x ˉ = mean of the sample n n = number of observations in the sample

Question 34

why do we divide by n-1

Answer 34

The square comes from summing up the deviations from the mean of these numbers will always be zero. The mean can be called the balance point.

Question 35

what is standard deviation

Answer 35

the square root of the variance

Question 36

give the equation for SD

Answer 36

SD=√(S^2 )

Question 37

evaluate SD

Answer 37

It is easy to interpret: unlike variance , the SD has the same unit as the data.

Question 38

which measures of central tendency are least affected by outliers

Answer 38

median trimmed mean mode