Psych 240- Stats
What is a histogram?
- divides up the range of variables into bins of equal size - counts how many individuals are in each bin - uses the heights of vertical bars to represent each value
What is the probability equation?
0 ≤ p ≤ 1
A probability of an event happening and not happening should always equal to
1
the area under the density curve always equals to
1
How does a sample differ from a population?
A population is the entire group that you want to draw conclusions about. A sample is the specific group that you will collect data from.
What is a contingency table?
A way to show two categorical variables
What is a bimodal, unimodal and uniform distribution?
Bimodal as two humps, unimodal has one hump and uniform has no humps
What is a discrete quantitative variable?
Can only take certain values and not fractions/decimals
What is a continuous quantitative variable?
Can take any numerical value
Kurtosis
Departure from normal
What is descriptive statistics?
Describing the data from our sample
What is an ordinal scale?
Difference between values have no real meaning It can only be interpreted the way we see it
What is a interval scale?
Difference between values mean the same thing ( can't be a zero)
What graph can help us find the outlier and skewed distribution?
Histogram
What is the variance?
How spread out values are from the mean
What does it mean when you have a low standard deviation?
It means the values are closer together
If there is an extreme outlier on a histogram, how will it affect the mean and the median?
It will skyrocket the mean and the median will barely move. The median would be used for the average instead.
Can a probability equal a negative number?
No, 0 ≤ p ≤ 1
When we are summing up a large number of independent influences, the sum will be
Normally distribution
What is a quantitative variable?
Quantitative variables are numeric like: Height, age, number of cars sold, SAT score
what is a ratio scale?
Similar to an interval scale but also has a true zero point
What is a population in psychology?
The group of people, animals, group, etc. you're interested in studying
What does this equation mean? p(event) = probability
The likely that an event would happen
What does a right skewed data mean?
The outlier( tail) is on the right side of the data
What is a unimodal distribution?
When the histogram has one hump
What is a bimodal distribution?
When the histogram has two humps
What is a density curve?
a curve to represent a continuous probability distribution
What is probability?
calculating the chances of the event not happening or happening.
What are the variables in a study?
characteristics or traits among subjects
Smaller variance means
closer to the mean
Is the normal distribution continuous or discrete?
continuous
To represent a continuous probability distribution we use a
density curve
is a binomial distribution discrete or continuous?
discrete
What is a categorical variable?
doesn't represent a number of something
What is random sampling? Ex. lottery ticket
everyone in the population has an equal chance of being studied
What is a z score? x, mu, o
how far a value is from the mean in standard deviation units x= the value you are interested u= mean o= standard deviation
How does a normal distribution differ from a binomial distribution?
it's continuous; unimodal and symmetrical
What is inferential statistics?
make inferences about the population based on the data
When the distribution is symmetrical then the
mean and median is similar
N (u,o)
mu= mean ó (sigma) = sd
X in binomial distribution means
number of times
n in binomial distribution means
number of trails
p in binomial distribution means
probability of the success
What does "success" mean in the probability distribution?
the event we're interested in looking at
What is the first quartile?
the lower half of median
what is a binomial distribution?
the probability distribution of the number of times that an event happens in n trials
what is the .68 rule ?
the probability of an outcome between 1 standard deviation above and below the mean is .68
what is the .95 rule?
the probability of an outcome between 2 standard deviation above and below the mean is .95
what is the .997 rule?
the probability of an outcome between 3 standard deviation above and below the mean is .997
What is statistics?
the science of data
What is the distribution of a variable?
the values that a variable has and frequency at which they occur
What is the response variable?
the variable that is doing the explaining
what is an explanation variable?
the variable you're trying to explain
What is the third quartile?
upper half of the median
