Flashcards in Psychology 202 - Test 1 Deck (36)

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1

## data

### information

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## statistics

### branch of mathematics focused on organization, analysis, and interpretation of a group of numbers

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## descriptive statistics

### used to describe a group of numbers from a study

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## inferential

### used to draw conclusions from collected data

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## variable

###
characteristic of something or someone that can have different vaules

i.e. people, [usually] mind

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## constant

###
if the characteristic does not/can not vary

- dependent on perspective

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## values

### numbr or category

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## score

###
particular value on a variable

- tells how much there is of what is being measured

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## equal-interval variable

###
a variable in which the numbers stand for approximately equal amounts of what is being measured

i.e. in stress rating, difference between 4 & 6 is the same as the difference between 7 & 9

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## ratio scale

###
used if the equal-interval variable has an absolute zero point

i.e. number of siblings > zero means something and is important

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## absolute zero point

###
value of zero on the variable indicates complete absence of the variable

i.e. number of siblings > zero = no siblings

12

## rank order variable

###
a variable where numbers stand ONLY for the relative ranking

- ordinal variables

- provides less info/less accurate than equal-interval but sometimes easier/only info available

i.e. olympics (1,2,3) but 1 & 2 can be close while three was far behind them

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## nominal variable

###
variable in which the values differ as names or categories

i.e. favorite sports team

*can go from nominal to numeric but not the other way around

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## discrete variable

### specific values and nothing in between

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## continuous variable

### has infinite number of values in between any two values

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## population

###
the entire group of people that is studied

- can range from small to the entire world depending on the question

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## sample

###
a subset of the population

- small/more manageable group to study

-(hopefully) identical to population > generalizability

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## frequency table

### table that lists all values that are possible along with the number of cases that have that value

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## relative frequency table

###
tells frequency AND frequency relative to other scores

- divide number of cases in each value by total number of cases

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## histogram

###
graphic representatio of frequency of scores

- x = possible values

- y = number of cases

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## number of peaks (histogram)

###
1 peak = unimodal

2 peaks = bimodal

3+ peaks = multimodal

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## symmetrical distributions

### roughly equal scores on both sides of the peak

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## skewed distributions

###
unequal scores on each side of the peak

- positively skewed > more scores on left side

- negatively skewed > more scores on the right side

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## normal curve

###
symmetrical, bell shaped curve that has changes in curve direction at exactly 1 standard deviation above and 1 standard deviation below the mean

- theoretical distribution

- mode, median, and mean are all exactly the same number

- Middle point = average point = most frequent point

- more scores you have = closer you get to normal distribution

- assume data would look like normal curve if we had enough

- 68.2% = 1 SD

- 95.4% = 2 SD

- 99.7% = 3 SD

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## platykurtic

###
most values have roughly the same frequency

- upside down plate

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## leptokurtic

###
very few values have a high frequency

- tower

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## measure of central tendency

###
single number that we use to describe a distribution of scores

- representative of all scores

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## mean

###
mathematical average of a group of scores

- μ = population, M = sample

- mean = Σx/N

- most stable measure of central tendency

- takes all scores into account

- can be value no one got

- incredibly sensative to outliers

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## mode

###
most frequent score in a distribution

- only measure that can be used with nominal data

- says nothing about other scores

-doesn't tell the placement of the score

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## median

###
score in the middle of a distribution

- scores in order from smallest to largest and find middle score

- can be the same as mode

- can be score no one has/received

- does not mean there is equality in the range

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## variability

### the amount of variation in a distribution of scores

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## range

###
the difference between the highest and lowest score

- very unstable

- no additional stats calculated

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## variance

###
measure of variability that considers how different each score in a distribution is from the mean

- extremely important in stats

- population = δ

- sample = SD

- variance = Σ(x - M)²/N

- SS = Σ(x - μ)²

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## standard deviation

###
the average amount that a set of scores differ from one another (how much scores vary)

- population =

- sample = SD

- standard deviation = √Σ(x - μ)²/N

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## z-score

###
number of standard deviations above or below the mean an actual score is

- standardizes scores

- z = (x - M)/SD

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