Chapter 1 - Basic Concepts

Question 1

what are statistics?

Answer 1

study of collecting, organizing and analyzing data (sample based on a population) to understand patterns and make decisions.

Question 2

why are statistics important?

Answer 2

to get answers.
eg. what forms of therapy are more effective?
education wise: use statistics in bachelors, masters, PhD, …

Question 3

do we all have an intuitive grasp of statistics? give an example.

Answer 3

yes we do. say flipping a coin 10 times. getting head 10 on 10 times is far more surprising then 5 out of 10 times.

Question 4

based of the example you just used, it landed 10/10 times heads. would you say the coin is fair?

Answer 4

no, we would be biased in some way. however, unusual does not mean impossible.

Question 5

what is the goal of statistics?

Answer 5

estimation

Question 6

in terms of the jelly bean example, what would be the sample? population?

Answer 6

the sample would be the portion that you decide to grab a handful of. the population is the entirety of the jelly beans in the jar.

Question 7

what would be more helpful? a small sample or a large sample?

Answer 7

• You find that 28% of the jelly beans are red in your large sample
• Your large sample has 25 jelly
  beans and 7 of them are red
• 7/25 = .28 = 28%
• How many red jelly beans do you think are in the jar?
• With only our sample, our best
  estimate is 28%
• Is this would be a good estimate?
• Another sample would likely
  have a slightly different
  number of red jelly beans
• It could have 28%, but it could
  also have more or less than 28%
  -it really depends just how big of a sample you pick up. if you pick up 95% of the jelly beans, then yes it is more likely to be accurate)

Question 8

psychology involves measuring things, what do psychologists measure? (3)

Answer 8

-construct: the “thing” to be measured (e.g. health)
-variable: physical or abstract attributes that we wish to measure, can have a specific measure. (e.g. # heart attacks in mtl over the past year)
-score: value that an individual has on a particular variable (e.g. yes or no to having a heart attack)

Question 9

what is the difference between data and datum?

Answer 9

data is plural
datum is singular

Question 10

what is an independent variable?

Answer 10

variable that you can manipulate or categorize (e.g. study time - minutes, hours or days)

Question 11

what is a dependent variable?

Answer 11

variable that you measure (e.g. grade - exam score, term GPA, cumulative GPA, etc.)

Question 12

what is a confounding variable?

Answer 12

varies systematically with the independent variable making it impossible to determine which drives the effect (e.g. cheating, copying, chat GPT) - not manipulating it but it can influence the independent variable.

Question 13

what is the difference between qualitative and quantitative?

Answer 13

qualitative = not numerical, things with names and values (e.g., hair colour, flavour of ice cream, etc.)

quantitative = numerical values, numbers

Question 14

what are the two sub-categories for qualitative variables?

Answer 14

nominal and ordinal

Question 15

what is a nominal variable?

Answer 15

-names with no natural ordering (e.g. blue is not bigger then orange)
* Sometimes called Categorical
Variables, as values can be
discrete categories
* E.g., Political party, Eye Colour,
Smartphone, Cookie Preference

Question 16

what is an ordinal value?
(*first version)

Answer 16

• rank order!
• between qualitative and quantitative, they have properties of both
• E.g., Marathon Runners; there
  are no equal intervals
  between those who finish 1st,
  2nd, 3rd, etc
• There is a natural order of
  scores, but no units of
  measurement

Question 17

what is an ordinal value?
(*second version)

Answer 17

letter grades. natural ordering but no unit! BUT can be converted to numbers and treated as intervals. qualitative!

Question 18

what are the two sub-categories for quantitative variables?

Answer 18

interval and ratio

Question 19

what is an interval variable?

Answer 19

-interval scales have equal units of measurement but no zero point.
-ALL ratio scales are equal interval scales, but NOT all equal interval scales are ratio scales.

Question 20

true or false? not all scales have absolute zeros.

Answer 20

true. kelvin vs celsius vs Fahrenheit

Question 21

true or false? Fahrenheit is an interval scale, not a ratio scale.

Answer 21

true

Question 22

what is a ratio variable?

Answer 22

-Ratio Scales have an
absolute zero and a unit of measurement
that corresponds to a constant physical quantity
* Ratio Scales can measure two values in
terms of their relative distance from zero
* E.g., 3ft tall versus 6 ft tall (2Xs from 0)
* Values can be Discrete or Continuous
* Integers/Whole Numbers VS Real Numbers

Question 23

what is the difference between a integer/whole number and a real number/continuous

Answer 23

integer = whole number (no decimals)
continuous = decimals

Question 24

recap!! name all four levels of measurements!

Answer 24

nominal, ordinal, interval and ratio.

Question 25

many variables are not physical (e.g. we can't measure intelligence with devices like a ruler). so, define psychological constructs and operational measures.

Answer 25

* Psychological Constructs: distinct abstract quantities that explain an aspect of behaviour but cannot be measured directly (e.g. depression) * Operational Measures: tool used to measure a psychological constructs.

Question 26

what is the difference between validity and reliability.

Answer 26

validity: a device is valid if it measures what it is suppose to measure. reliability: a device is reliable if it produces similar if not identical measurements each time it is applied to the same object.

Question 27

what is the measurement error?

Answer 27

each time something is measured a slightly different score will be obtained. (nothing can measure without error)

Question 28

difference between populations and samples.

Answer 28

populations: compromises all scores of a variable (aka parameter) samples: subset of a population (aka statistics)

Question 29

define parameters.

Answer 29

parameters are characteristics of the population (real entities)

Question 30

how are parameters denoted?

Answer 30

greek letters (miew, variants, sigma and rho)

Question 31

define statistics.

Answer 31

numerical characteristics of a sample (guesses)

Question 32

how are statistics denoted?

Answer 32

by lower case Latin letters: m, s^2, s, r

Question 33

what is a sampling bias?

Answer 33

- not all members of the population had an equal chance of being selected in the sample. -Leads to statistics being poor estimators of parameters`

Question 34

what helps reduce sampling bias?

Answer 34

simple random sampling: In a truly random sample each unit has an equal chance of being sampled

Question 35

Do we think the scores of the sample will equal the scores of the population?

Answer 35

no! it is highly unlikely. A sample statistic is often never exactly equal to the population parameter.

Question 36

what is the difference between the population parameter and the sample statistic?

Answer 36

sampling error

Question 37

observed score = ?

Answer 37

observed score = true score + error

Question 38

does sampling error = sampling bias?

Answer 38

no! sampling error can not be avoided, but bias theoretically can.

Question 39

true or false? 1. the smaller the sample, the bigger the sampling error. 2. the bigger the sample, the smaller the sampling error

Answer 39

1. true! 2. true!