psyc test 3

Question 1

What is statistics?

Answer 1

A branch of mathematics devoted to the collection, compilation, display and interpretation of numerical data.

Question 2

What are the two types of statistics?

Answer 2

Inferential and descriptive

Question 3

What is descriptive statistics

Answer 3

Presenting, organizing and summarizing data

Question 4

What is inferential statistics?

Answer 4

Drawing conclusions about a population based on data observed in a sample (hypothesis testing)

Question 5

What do we need statistics for?

Answer 5

Description
Prediction
Causation

Question 6

What is description?

Answer 6

aims to describe the prevalence of something (prevalence of heavy drinking)

Question 7

What is Prediction?

Answer 7

aims to forecast likely outcomes

Question 8

What is Causation?

Answer 8

aims to establish cause and effect

Question 9

What are units? Where are they found?

Answer 9

the objects we are studying (people, companies, students)
Usually the rows in the data set

Question 10

What are variables? Where are they found?

Answer 10

measurements that vary across people (height, weight)
Usually the columns

Question 11

What is the dependent variable? What are other words for it?

Answer 11

The variable to be explained (outcome variable, response variable, primary endpoint)

Question 12

What is the independent variable? What are other words for it?

Answer 12

Determinants of the dependent variable (explanatory variable, predictor variable, covariate)

Question 13

What is the control variable? What is another word for it?

Answer 13

Any other variable that may plausibly alter the relationship between the IV and the DV (covariate)

Question 14

What are the 4 types of measurements/ variables?

Answer 14

Nominal, ordinal, continuous- interval, continuous- ratio

Question 15

What are nominal variables and give an example?

Answer 15

The data are categorized with no inherent order (hair colour)

Question 16

What are ordinal variables and give an example?

Answer 16

The data are categorized and ranked (score on likert scale, year of university)

Question 17

What is interval data and give an example?

Answer 17

Data that is continuous, ranked and evenly spaced (test scores)

Question 18

What is ratio data and give an example?

Answer 18

Data is continuous, evenly spaced and has a natural zero (height)

Question 19

What is the first step to describing data?

Answer 19

categories and sort it

Question 20

What is a frequency table? And how are they formatted?

Answer 20

A table that lists each value and the number of times it appears

Tables are listed from highest to lowest value and each value is included even if tis frequency is zero

Question 21

What is relative frequency?

Answer 21

proportion. dive the frequency by the total n

Question 22

What are grouped frequency tables and why are they used?

Answer 22

Are data is too speed out (too many 0 frequencies). We create grouped intervals that has equal width and always start with a multiple of the width

Question 23

What is a measure of central tendency? what are the measures of central tendency?

Answer 23

The value of a “typical” observation. Mean, mode, median

Question 24

What is the mode?

Answer 24

most common value

Question 25

What are the 4 types of modes you can have?

Answer 25

unimodal, bimodal, multimodal, amodal

Question 26

What type of data can you use for median?

Answer 26

Since It has to be ordered it can only be used for ordinal, ration or interval

Question 27

What type of data can you use for mean?

Answer 27

interval or ratio scales

Question 28

What types of data are the mean, median and mode most appropriate for

Answer 28

Mean is best for continuous Median is best for ordinal Mode is best for nominal

Question 29

What is a histogram?

Answer 29

Plots frequency data for continuous variables. The bars all touch and a space means there is no data for that value

Question 30

What is a bar chart? And what are they used for?

Answer 30

Used for ordinal or nominal data Bars do not touch and represent categories. Shows the frequency. The order doesn't matter for nominal

Question 31

When will the mode, median and mean all be the same

Answer 31

When the data is symmetrical and unimodal

Question 32

What happens if you have a skewed distribution?

Answer 32

The mean will be pulled towards the skew and the median will be between the mode and the mean

Question 33

What happens to the mean if there is an extreme skew (extreme outliers)

Answer 33

It is biased towards the outliers

Question 34

What type of skew extends out to the left

Answer 34

negative

Question 35

What type of skew extends out to the right

Answer 35

positive

Question 36

What are the measures of variability?

Answer 36

Range, SD, interquartile range

Question 37

What is the range?

Answer 37

Difference between the lowest and the highest score

Question 38

What is the inter-quartile range (IQR)

Answer 38

measure of variability in non-normally distributed data. Separates data into 4 equal parts and considers the different between the lower and upper quartile

Question 39

What is standard deviation?

Answer 39

measure of how close values are to the mean

Question 40

What does a low SD mean?

Answer 40

Values are close to the mean

Question 41

What does a high SD mean?

Answer 41

values are spread out

Question 42

What is an outlier? Are all extreme scores bad?

Answer 42

An extreme score that is much higher or lower than the rest of the scores. Some may be important to our data

Question 43

What can cause outliers?

Answer 43

errors, misunderstandings, equipment failures

Question 44

What are the mean, median and mode affected by outliers?

Answer 44

Mean is most sensitive and will be pulled towards the outlier Median is not really impacted unless there are many outliers Mode is not impacted

Question 45

How are the range and SD affected by outliers

Answer 45

SD will be larger Range will be greatly impacted

Question 46

What is a z-score? What are the units?

Answer 46

How far an individual score is from the mean. Measures exactly how many standard deviations above or below the mean a data point is. Z-score is standardized so it has no units

Question 47

What can Z scores be used for?

Answer 47

to determine if a value is an outlier or not

Question 48

What is the formula for Z-score?

Answer 48

z= (X-M)/SD

Question 49

Why is the normal distribution important

Answer 49

Statistical test assumptions Method selection between parametric and non parametric methods Data transformations

Question 50

What tests assume that data follows a normal distribution?

Answer 50

t-test, ANOVA

Question 51

What is parametric vs non-parametric methods?

Answer 51

Parametric assumes normality

Question 52

What is data transformation?

Answer 52

transforming data to meet normality assumptions

Question 53

What percentage of data is within 1 SD, 2SD, or 3 SD?

Answer 53

68% within 1SD 95% within 2SD 99.7 within 3 SD

Question 54

What is skewness

Answer 54

Whether the data is distributed symmetrically around the mean. Describes asymmetry of distribution

Question 55

What does 0 represent for skewness. What does positive represent for skewness What does negative represent for skewness? Draw Skewness

Answer 55

0= perfect symmetry negative = left skew positive = right skew

Question 56

What is kurtosis?

Answer 56

whether data is peaked or flat. heaviness of a distributions tails relative to a normal distribution

Question 57

When is kurtosis high? when is it low?

Answer 57

high when data is near the mean low when data is spread out

Question 58

What is Platykurtic What is mesokurtic What is leptokurtic?

Answer 58

<3 is platykurtic = flat = 3 mesokurtic =normal leptokurtic >3 = tall

Question 59

What the 2 ways to assess normality?

Answer 59

Visually or with statistical analyses

Question 60

What are the two ways to visually assess normality?

Answer 60

Using a histogram or Q-Q-plots

Question 61

What do Q-Q plots show?

Answer 61

If data is normal in a Q-Q test, the data will follow the diagonal line. If it is skewed it will deviate

Question 62

What are types of statistical analyses that can assess normality?

Answer 62

Skewness score Kurtosis score Shapiro Wilks for Normality

Question 63

What is Shapiro Wilks test for normality?

Answer 63

Means data is not significantly different from a normal distribution. Use p >.05 to

Question 64

What happens to power when there are more participants? What is the risk?

Answer 64

Power increases with more participants, it becomes more likely to detect small or subtle effects. This can also increase the likely hood of finding a false positive since there's a greater sensitivity to detect any signal, whether it's a true effect or just random noise.

Question 65

What should determine your distribution model?

Answer 65

The nature of the data and the phenomenon it represents