Module 1/2: Lecture Notes Flashcards
Parameters
A population parameter is a numerical value that describes a characteristic of a population. For example, the population mean height of all students in a school is a population parameter.
Statistics
Numerical description of a sample characteristic
What is the difference between a parameter and a statistic?
The difference between a parameter vs a statistic is that a parameter is a fixed measure describing the whole population, while a statistic is a characteristic of a sample, a portion of the target population.
Descriptive statistics (3)
What it is+ what it does+ ex
- The organization, summarization and display of data
- simplifies data to make large groups of numbers easier to grasp
- Ex: Did you go away for break? -> ask everyone and find the amount that stayed and went away. -> use % to summarize
Inferential statistics (3)
What it does+ generalize+ draw conclusion
- Draw conclusions about a population based on data from a sample
- Generalize about a characteristic we cannot measure directly
- Enable researchers to draw conclusions when it might be impossible to measure all members of the population of interest
Discrete data is
categorical
Quantitative Data (2)
What it is+how is it presented?
- Information about quantities; How much or how many of something
- Presented as a set of numbers
Continous Data
Take on any value in some interval and are not restricted to any list of values value in some interval
Discrete data
Can be listed
What level of measurement is continous?
Ratio, Interval
Which level of measurement can quantify the difference between values?
Interval, Ratio
Which level of measurement can add/subtract?
interval/ratio
Which level of measurement can multiply/divide?
ratio
Which level of measurement has inherent true values?
ratio
Variables(3)
What it is+ can be…
- Something that varies
- Can be a few levels (ex: 2-4 for categorical, left or right handed)
- Can have many values (Continous data)
Experimental Study (2)
What it is+ what researchers do
- A treatment, proedure or program is intentionally introduced and a result or outcome is observed
- Researchers compares outcomes between those who received treatment and those who did not
Independent variable
Actively manipulated
Dependent Variable
Changes as a result of manipulation of IV
Confounding variables
What it is+ varies with + impossible to…
- Anything that could cause change in B that is not A
- varies with the IV
- Impossible to identify the cause of any change in the DV
Validity
Does the experiment measure what it is intended to measure
Reliability
refers to how consistently a method measures something
Frequency Tables
Shows discrete data values along with frequency of each
Unimodal
One highest frequency or value
Skewed distributions
Have many more scores on one side of a distribution than on the other side
Negative skew
Left tail is longer
Positive skew
Right tail is longer
Way to measure central tendency (3)
Mean
Mode
Median
Mean
A set of scores is the sum of the scores divided by the number of scores
Median
The midpoint
Mode
The value that occurs the most often. It also represents the highest peak or column in a graphed frequency distribution.
Central tendacy of positive skew
Central Tendency of Negative Skew
Population mean
Sample Mean
Deviation
The distance of a score x from the mean of the distribution it is included in
Deviation of the entire population
(x-μ)
distance between data point x and the population mean
Deviation of sample
(x-X̄)
distance between a point x and the sample mean x-bar
Why do we square deviance rather then absolute it?
Because you dont want to underplay any outliers
When a sample variance is calculated, the sum of the values is divided by n-1 instead of n. This is done to —–
correct for the tendency of the sample variance to slightly underestimate the population variance
Population standard deviation symbol
σ
sigma
Sample standard deviation symbol
s
What is standard deviation?
It is a measure of the variability within a distribution
A data point that is several standard deviation from the mean may be ….
just due to random variation but it could also signify an unsual event that needs to be investigated
What do Z scores do?
Gives the distance in standard deviations from a data point to the mean of the distribution it is included in
How are Z scores calculated?
Multiplying the z-score by the standard deviation tells us—– adding that to the mean gives—–
- how far the raw data value is from the mean in terms of the original data values
- the exact location or data point
Qualitative data
Presented as
presented as names or categories
