Week 1 lecture CNTD, Standard deviation, z scores, measurement, COIS, correlation and psychometrics

Question 1

What is a standard deviation and standard error of the mean?

Answer 1

SD: Variance gives us a measure in units squared, taking square root of variation gives SD

SEM: measure of spread, what SD would look like if measured in real world

Question 2

What are the 5 measures of spread? (CRISS)

Answer 2

Confidence intervals
Range
interquartile range
Standard deviation
Standard error of mean

Question 3

What are confidence intervals and what represents them? (what couldn’t you figure out how to make elliott’s first assignment ?) 95/100…

Answer 3

Defines range taht will theoretically capture true mean 95% of the time (95 times out of 100 )
Represented by error bars

Question 4

Why does the mean, mean nothing and what’s possible when a chart doesn’t have this?

Answer 4

Means nothing as there’s no measure of spread, when a chart doesn’t have a measure of spread they either are stupid or think im stupid

Question 5

How do we know when error bars are significant or insignificant?

Answer 5

When error bars overlap quite a bit means probably insignificant, when error bars do not overlap significantly means it’s usually statistically significant

Question 6

What three things all represent the same thing? (squares,very,S..)

Answer 6

sum of squares variance and standard deviation all represent same thing just different amounts

Question 7

What are z scores and it’s formula?

Answer 7

Expresses score in how many Sd’s it is away from the mean

z= x-x(bar) ~(divided) SD

Question 8

What are the 5 property’s of z scores ? cuts off top/bottom, lie between…
(cuts off 2…, lies: 1..,2..,3..) (95% of,99% of,99.9 %of)

Answer 8

1.96 cuts off top 2.5 percent of distribution

-1.96 cuts off bottom 2.5 percent of distribution

95 percent of z scores lie between 1.96 and -1.96

99 percent of z scores lie between 2.58 and -2.58

99.9 percent of z scores lie between 3.29 and -3.29

Question 9

what does p=0.49mean as an alpha level and what does it mean if p=0.5 is alpha level of expirement?

Answer 9

P=0.49- less than 5 times out of 100 an error can happen and we are okay with that, alpha level set to show error we are okay with getting

P=0.5- we are okay with error being 5/100 (error rate we are okay with having)

Question 10

What is a correlation and it’s 3 factors? (change, weight scale, two things don’t cause eachother)

Answer 10

Co variation/relation between 2 variables

3 factors:
variables change together
usually scale variables
correlation doesn’t mean causation

Question 11

what is a correlation coefficient and it’s 3 factors (yay or nay, 1, STRONG based upon..)

Answer 11

statistic that quantifys a relation between two variables

3 factors
can be positive or negative
falls between -1.00 and 1.00
value of number indicates strength

Question 12

What is a positive and negative correlation and what kind of relation do they have? (smiles for positive)

Answer 12

Positive : One variable has high score and other variable tends to as well
-direct relation between two variables

Negative: One variable has high score while other has low score
-inverse relation between variables

Question 13

What are two scale variables (NOIR) and what’s a pearson correlation coefficient and what two letters can it be represented by? (what do you get when making personal best)?

Answer 13

two scale variables: interval and ratio

Pearson coefficient is a statistic that quantifys linear relation between two variables

Can be represented by Italic R for sample data or Italic P for population parameter

Question 14

How many strengths of correlation are there and what numbers do they represent? ( like shirt sizes)

Answer 14

Small- 0.10
Medium-0.30
Large- 0.5

Question 15

What are the two limitations of correlation and what does it mean? (no full popu…, switch from negative to positive)

Answer 15

Restricted range- smaller range than full population, correlation can become smaller

Effect of outlier- outlier can make correlation much stronger than supposed to and even change from negative to a positive

Question 16

What are the 6 steps to correlation hypothesis testing? ( Identify, state,find and determine, determine, calculate, make..)

Answer 16

1. identify population, distribution and assumptions
   2) state null and research hypothesis
   3) Find and determine characteristics and compare
   4) determine cortical values
   5) calculate statistics and tests
   6) make a decision

Question 17

What do psychometric and psychometricians do? (2 factors) development..

Answer 17

Psychometric are used in development of tests and measures
psychometricians use correlation to examine 2 aspects of development of measures
2 Factors
1) reliability 2) validity

Question 18

Why are correlations used in psychometrics?

Answer 18

to help assess reliability of pro sports team or establish validity of personality test

Question 19

What are the 2 meanings of stats and the 2 ways to represent data? (maths) (g.., history..)

Answer 19

2 meanings of Stats: 1) field that applys to mathematical techniques to interpret and summarize data 2) Mathematical techniques themselves

2 ways to represent data
1) frequency distributions (histograms)
2) Graphs

Question 20

What does a frequency histogram represent and when do the bars touch and not touch ? (gender,age and weight)

Answer 20

Represents frequency data in bar form

Non continuous variables (gender) bars don’t touch

Continuous variables (age, weight) do touch

Question 21

What type of statistics is used to measure thousands of high school grade point averages and what else does it measure? (2) measures: CT, V

Answer 21

Descriptive statistics to obtain precise scores, measures central tendency and variability

Question 22

Where is the frequency of scores the strongest and weakest?

Answer 22

Strongest/greatest near the mean and progressively decreases towards extremes (ends)

Question 23

What are the three frequency scores? 60.. something falls between what and what SD’s away from the mean?) (-1,2,-3)

Answer 23

68 % of scores fall between -1 and 1 standard deviations away from the mean

95% fall between -2 and 2 SD’s away from mean

99% fall between -3 and 3 SD’s away from mean

Question 24

What’s the difference between Parametric and Non parametric stats(and what’s another name for it)? (one needs somthing, other doesn’t need it)

Answer 24

Parametric needs population parameters to do inferential procedures

Non parametric can be called distribution free stats as it doesn’t need population parameters to do inferential procedures

Question 25

What kind of data is non parametric and parametric stats, and what types of tests fall under both (2 each) ?(sneaky and always going..)

Answer 25

Non parametric- discrete data : Chi square, Kruskal wallis,spearmen,kendall’s tau

Parametric- continuous data : T tests, Anova

Question 26

Which tail design has more power (1 or two tail) and why?

Answer 26

One tail designs have more power as they can detect significant difference because they’re less conservative (more likely to find something)

Question 27

What does a perfect correlation (constant) mean and inferential statistics? (inferences)

Answer 27

Perfect correlation means variables always stay the same

Inferential stats is information about a sample that can be used to make inferences about a population