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Stats Exam 1
Terms in this set (80)
The complete set of individuals, objects, or scores that the investigator is interested in studying
Subset of the population.
-Collects data on a smaller group of subjects than the entire population
Variable that is systematically manipulated by the investigator
The variable that the investigator measures to determine the effects of the independent variable
The measures that are made on the subjects of an experiment are called data
A number calculated on sample data that quantifies a characteristic of the sample
A number calculated on population data that quantifies a characteristic of the population
Any property or characteristic of some event, object, or person that may have different values at different times depending on the conditions
Does NOT have different values at different times
Describe and be able to differentiate between the four methods for establishing truth.
We consider something to be true bc of tradition or because some person of distinction says it is true (Someone says god is true and we believe it)
Uses reasoning alone to arrive at knowledge. Assumes that if the premises are sound and the reasoning is carrier out correctly according to the rules of logic, then the conclusions will yield truth.
All stats professors are interesting people. Mr. X is a stats professor thus Mr. X is an interesting person
The sudden insight, the clarifying idea that springs into consciousness all at once as a whole.
Uses BOTH reasoning and intuition for establishing the truth, its reliance on objective assessment is what differentiates this method from others
More on Scientific Method
By some means, usually by reasoning deductively from existing theory or inductively from existing facts or through intuition
Compare and contrast observational and experimental research.
-No variables are actively manipulated by the investigator
-Cannot determine causality
Naturalistic observation research
Goal is to obtain an accurate description of the situation being studied
-Much of anthropological and etiological research is done this way
Parameter estimation research
conducted on samples to estimate the level of one or more population characteristics (Population average or percent)
-Surveys fall into this category
Investigator focuses on attention on two or more variables to determine whether they are related
-Are obesity and heart disease related
An attempt is made to determine whether changes in one variable causes changes in another.
-An independent variable is manipulated and its effect on some dependent variable is studied
Know the basic requirements to establish a causal relationship between variables.
-There is a difference between control groups
-The experiment has to cause a change
Concerned with techniques that are used to describe or characterize the obtained data
Involves techniques that use the obtained sample data to infer to population
*Me and Rach smoke out of the 4 of us. So 50% us (pop) smoke
Know the difference between a statistic and a parameter.
Be able to describe why random sampling is important in research.
-Allows the laws of probability
-Representative of the population
-Everyone has a chance to be selected
Understand what is meant by "parameter estimation."
Type of observational study in which the goal is to determine a characteristic of a population. EX:Mean age of all psych majors at NAU
*Just like inferential
Understand subscripts as they related to items in a set of numbers.
-Symbols standing for variables
Know the characteristics of the scales of measurement and be able to provide examples of each.
Nominal, ordinal. interval, ration
-Categorizes for the units
-One of the lowest levels of measurement
-Used with variables that are qualitative in nature than than quantitativee
-Brands of jogging shoes, fruits, types of music
-One in which the numbers o the scale represents rank orderings, rather than raw score magnitude
-Represents the next higher level of measurement
-Low level of property of magnitude
-an A in a class VS a B
-One in which the units represent raw score magnitudes, there are equal intervals between adjacent units on the scale, and there is no absolute zero point
-Represents a higher level of measurement than the ordinal.
*NO MEANINGFUL ZERO
Equal range of numbers (5-9)
Other info on Interval
-Possess properties of magnitude and equal interval between adjacent units but doesn't have an absolute zero point
*The celsius of temp measurement is a good EX
One in which the units represent raw score magnitudes, there are equal intervals between adjacent units on the scale, and there is an absolute zero point.
-Weight! Something can actually weight 0
More on ratio scale
The next and highest level of measurement.
-Has all properties of an interval scale and, in addition, has an absolute zero
One in which there are no possible values between adjacent units on the scale
*Rate how much you like pizza scale 1-5
One that theoretically can have an infinite number of values between adjacent units on the scale
*Population! Or weight! It can keep going
WRITE IT OUT
If the second number after the decimal is even and the third number after the decimal is 5 you round down. Opposite if odd b
Establishment of lower and upper real limits of a continuous variable
-Weighed in at 180 then starved herself and weighed in again at 180. You would be justified in saying 179 when the needle is below the halfway point between 179 and 180but below the halfway point.
-We would record 180 pounds if the needle was above 180 but below the halfway point between 180 and 181 pounds
Compare and contrast grouped and ungrouped frequency distributions and provide an example of a situation in which each would be appropriate.
Grouped frequency distribution
-When there are many scores and range widely, as they do on the statistics exam we have been considering listing individual scores results in many values with a frequency distribution of zero and display from which it is difficult to visualize the shape of the distribution and its central tendency
Ungrouped frequency distribution
List the scores by how frequently they occurred
Range of frequency
Every single individual
Compare and contrast percentile point and percentile rank
Data point at which a specified percentage of scores fall below
*How old are 70% of people
Where the distribution where a data point is ranked
*What percent of people are 70%
Be able to recognize, define, and state a use for:
A bar graph
-Nominal or ordinal data
-How many people like each flavor of chocolate (vanilla, strawberry, chocolate)
-Interval or ratio
-Age(smooth flow between the groups=smooth curve)
A frequency polygon
-Makes a weird shape
-In each interval and connect the highest points of each
A stem and leaf plot
Go to powerpoint
A box plot
Be able to recognize and define:
A symmetrical curve
50% of scores on the right and 50% of scores on the left and mean, median, and mode in the middle
Understand the use of and be able to create or calculate the following:
Depended, reactive variable=Y Axis
Manipulated, independent variable= X axis
Understand the use of and be able to create or calculate the following:
Ungrouped frequency distribution.
-mean changes drastically based on outliers
-Least sensitive to extreme scores
-Entirely based on the exact scores in it
-Good if we have nominal or ordinal where the exact numbers don't matter as much
Explain why the formulas for calculating the population and sample standard deviations are different.
-Because the amount of variance in a sample is higher than the population. BC there are a smaller number of participants in it
Specify how the mean, median, and mode are affected by skew in a unimodal distribution and, given a skewed unimodal distribution, be able to label each measure of central tendency.
-The median is always going to be between the mode and the mean
-And the mode is always at the highest point
-The mean will always be closest to the tail
-The median will always be furthest away from the tail
Describe the basic properties of the normal curve (symmetry, etc.).
Mean, median, mode are always in the middle
-50% of either scores are on opposite sides
-Extends infinitely in either away
-The tails never reach zero
Describe the link between the area under a normal curve and the percentage of scores contained within the area.
Asking for a z scores
-The further out from the center point you get the less percentage of scores you get
Define a z score and explain why it is known as a "standard" score.
-Z score=Standard way of measuring in units of standard deviations out from the center
-They have a confidence of 95 percent
Explain the three main functions of a z distribution.
1. Z scores have the same shape as the set of raw scores
2. The mean of the Z scores always equals zero
3.Standard deviation of Z scores always equals one
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