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41 Cards in this Set

  • Front
  • Back
the researcher merely observes what ishappening or what has happened in the past and tries to draw conclusions basedon these observations
Observational Study
the researcher manipulated one of thevariables and tries to determine how the manipulation influences othervariables
Experimental Study
a characteristic or measure obtained by using the data values from a sample.


a characteristic or measure obtained by using all the data values from a specific population


consists of all subjects being studied


a group of subjects from the population


the organization of raw data in table form, using classes and frequencies

Frequency Distribution

raw data values are placed into a quantitative or qualitative category called a class

Class limits

the largest and smallest value that can be included in that class

Upper and lower class limits

the number of values in each class


numbers used to separate the classes so that there are no gaps in the frequency distribution

Class boundaries

is found by subtracting the lower (or upper) class limit of one class from the lower (or upper) class limit of the next class

Class width

Class midpoint

Xm= (Lower Limit+Upper limit)/2
shows the number of data values that are less than or equal to a specific value ; found by adding the frequencies of the classes less than or equal to the upper class boundary of a specific class ; shows the number of data values that are less than or equal to a specific value ; found by adding the frequencies of the classes less than or equal to the upper class boundary of a specific class D

Cumulative frequency distribution

when the range of data values is very small a frequency distribution can be constructed using single data values for each class

Ungrouped Frequency distribution

a graph that displays the data by using contiguous vertical bars (unless the frequency of the class is 0) of various heights to represent the frequency of the classes


a graph that displays the data by using lines that connect points plotted for the frequencies at the midpoints of the classes. The frequencies are represented in the heights of the points

frequency polygon

(aka the cumulative frequency graph) is a graph that represents the cumulative frequencies of the classes in a frequency distribution


Variance Equation


Standard deviation equation





median for all values that fall below the median


median for all the data values that are above the median



Box plot

a graph of a data set obtained by drawing a horizontal line from the minimum data value to Q1 , drawing a horizontal line from Q3 to the maximum data value, and drawing a box whose vertical sides pass through Q1 and Q3 with a vertical line inside the box passing through the median

box plot

cannot occur at the same time (have no outcomes in common)

Mutually Exclusive events

The chance of an event occurring


the probability of event E is a number (either a fraction or a decimal) between and including 0 and 1. This is denoted by 0≤P(E) ≤ 1

Probability rule 1

If an event E can occur (i.e., the event contains no members in the same sample space), its probability is 0.

Probability Rule 2

If an event E is certain, then the probability of E is 1.

Probability Rule 3

The Sum of the Probabilities of all the outcomes in the sample space is 1

Probability Rule 4




Probability rule for complementary events

Formula for emprical probability

P(E)= (frequency for the class)/(total frequencies in the distribution)=f/n� distribution)=f/n

Properties of a Binomial experiment

Fixed number of trials

Each trial can only have two outcomes or outcomes that can be reduced to two outcomes. These can be considered either a success or a fail

The outcomes of each trial must be independent of one another

The probability of a success must remain the same for each trial

the outcomes of a binomial experiment

Binomial distribution

a continuous, symmetric, bell-shaped distribution of a variable

Normal Distribution

Properties of Normal Distribution

Bell shaped

Mean, median, and mode are located at the center


The curve is symmetric about the mean

computed from the same sample data measures the strength and direction of a linear relationship between two quantitative variables. The symbol for the population correlation coefficient is ρ (Greek letter rh�)

Correlation Coefficient

Equation for Correlation Coefficient

r=(n(Σxy)−(Σx)(Σy))/√([n(Σx^2 )−(Σx)^2 ][n(Σy^2 )−(Σy)^2])
a statistical test for the mean of a population. It can be used when n≥30 or when the population is normally distributed and σ is known