Stats - Statistics Flashcards
What are the 4 types of data?
Nominal, ordinal, interval and ratio (NOIR)
What 2 types of data - when the person is given a score or numerical value?
Interval or ratio data
What 2 types of data - when the person is assigned to a category or tallied up as one point in a given category? (voting democrat or republican?)
Nominal or ordinal data
If there’s only two categories with nominal data what’s it called? (gender - female or male)
Dichotomous
What is interval or ratio data frequently called?
Continuous
What’s data involves tallying people and involves putting people into non-ordered categories(e.g., gender or ethnicity), which can then be converted into a percentage?
Nominal data
What data involves tallying people to see which ordered category each person falls into or we measure them on likert scales? (e.g., first born, second born, third born? or freshmen, sophomore, junior?)
Ordinal data
What data involves obtaining numerical scores where the score values have equal intervals? - there is no zero (IQ test) or there’s no absolute zero (temperature)
Interval data
What data involves taking numerical scores for each person where the score values have equal intervals and an absolute zero (income, number of children, score on an exam)
Ratio data
What type of statistics describe what data (DV) are being collected?
Descriptive statistics
What type of statistics has the goal of making inferences about the population from the sample?
Inferential
When we are interested in measures of central tendency, variability and graphs are we looking at group data or individual scores relative to the whole group?
Group data
What are the three measures of central tendency
Mean, median and mode
What is the mean and how is it calculated?
- the arithmetic average of a group of data
- it’s calculated by adding up all the scores in the group & dividing it by the total number of scores
What is the median?
the number that corresponds to the 50th percentile - where half the people are above the median and half the people are below it (MiDdle = MeDian)
What’s the mode?
the most frequently occurring score (MOde = MOst)
When data is skewed or there’s extreme scores do you use mode, median or mean?
Median is preferred
What are the 3 elements of measures of variability
standard deviation, variance & range
What is the measure of average deviation or spread from the mean in a given set of scores?
Standard deviation
E.g.,
- Set 1: 8, 10 & 12
- Set 2: 2, 10 & 18
- both have the same mean
- Set 2 has a larger standard deviation (spread)
What the name of when the standard deviation squared?
Variance
What’s the name of the difference between the highest score and the lowest score?
Range
What type of data are graphed using a bar graph?
Nominal or ordinal
The vertical line that goes up and down on a graph is called the
Y-axis
The horizontal line that goes from right to left on a graph is called
X-axis
Does the X or Y axis represent the categories (what two datas) or the scores (what two datas)
X-Axis
categories: nominal or ordinal data
scores: interval or ratio data
Does the X or Y axis represent the frequency
Y axis
How are percentile ranks depicted with the line on a graph?
flat or rectangular
What two datas are represented on a graph with curves?
Interval or ratio data
What type of skew has the mode as the lowest value and the mean has the highest value
Positive skew
What type of skew has the mean as the lowest value and the mode as the highest value
Negative skew
Which skew has the tail pointed to the left and which skew has tail pointed to the right
Positive = right tail end
Negative = left tail end
On a positive skew, what has the highest value, median, mode or mean
mean
What the most detailed and most specific value that tells us exactly how someone did relative to a group?
Percentile ranks
Percentile ranks are considered ______ ________ scores
Norm reference scores (comparing you to the group)
What’s the mean of z scores and what’s the standard deviation
mean = 0
standard deviation = 1
What’s the mean of t-scores and the standard deviation?
mean = 50
standard deviation = 10
What’s the mean of IQ scores and the standard deviation
mean = 100
standard deviation = 15
What percentage of people will be in between +1 and -1
68%
What’s the distribution of Ranks (Percentile Rank) within a bell curve in correlation to the z-scores
Z score = PR
-3 = 0.1
-2 = 2.5
-1 = 16
0 = 50
1 = 84
2 = 97.5
3 = 99.9
What’s the percentage of people between +2 and -2?
95%
What’s the percentage of people between +3 and -3
99%
If equal amount of bonus points were given to someone in the 50th percentile rank as someone in the 97.5 percentile rank, which one will have a greater change in PR?
The person who was initially in the 50th percentile or mid range rank
What formula can help you find the z-score?
(raw score - mean) divided by the standard deviation
With population mean and the population standard deviation which one is sigma and which one is mu
Sigma = population standard deviation
Mu = population mean
What are population values referred to as?
parameters
What are sample values referred to as?
Statistics
What does sampling error mean?
that our sample does not perfectly represent the population - it’s a little off
How do we know there’s a sampling error?
when taking a random sample of people like 25 people, the mean won’t be exactly 100, while the population mean is 100
Formula for the standard error of the mean:
Sx= SDpop/square root of the sample size (N)
With the standard error of the mean formula, the standard error of the mean has what relation to the standard deviation of the population & what relation to the square root of the sample size
standard deviation of the population = direct relationship
sample size = inverse relationship
To reduce the standard error of the mean, would you have to increase or decrease the standard deviation of the population and the sample size?
decrease the standard deviation
increase the sample size
What’s the most critical aspect of inferential statistics?
hypothesis testing
Are hypotheses expressed in terms of the sample or the population
Population, even though you test it using samples
What does the null hypothesis state regarding group differences
That there is no difference between groups
What is a researcher trying to do with the null hypothesis
Reject the null hypothesis meaning wanting to reject that there’s no differences by concluding there are differences between groups
Where is the rejection region or the region of unlikely values on the bell curve?
within the tail-end of the curve
The alpha region refers to what
the size of the rejection region or region of unlikely region
Do you accept or reject the null hypothesis when it’s in the rejection region?
Reject - which is what a researcher is hoping for
What kind of error is it called when we reject the null but later on, it turns out to be a mistake
Type 1 Error (reject = 1 C = type 1)
If your alpha score is 0.05 or 0.01 how likely is it to have made a type 1 error?
0.05 = 5% chance
0.01 = 1% chance
What kind of error happens when you accept the null when in fact there is significance
Type 2 error (accept = 2 C’s = type 2)
If you correctly reject the null when significance is found
Power = we are all after power and power is what we want
Does power and alpha have an indirect or a direct relationship?
Direct: as power increases so does alpha
Does power and beta have an indirect or direct relationship?
indirect
When the null is accepted and this decision is correct what’s it called?
It has no name
