Sampling Distribution of Sample Means
Distribution of the sample means that is obtained when we repeatedly draw samples of the same size from the same population
Probability distribution
Collection of values of random variable along with their corresponding probabilities
statistic
Measured characteristic of a sample
Density Curve
Graph of a continous probability distribution
Hypothesis
statement or claim about some property of a population
Hypothesis test
Method for testing claims made about populations; also called test of significance
Linear Correlation Co-efficient
measure of the strength of the relationship between two variables
Normal Distribution
bell-shaped probability distribution described algebraically by formula
Degree of freedom
number of values that are free to vary after certain restrictions have been imposed on all values
Measure of Variation
any of several measures designed to reflect the amount of variation or spread for a set of values
Bi Modal
have 2 modes
Census
collection of data from every element in a population
class mid-points
In a class of a frequency distribution, the value midway between the lower class limit and the upper class limit
class width
The difference between 2 consecutive lower class limits in a frequency distribution
Expected Variable
For a discrete random variable, the mean value of the outcome
Simple Random
Sample of a particular size selected so that every possible sample of the same size has the same chance of being chosen
Ordinal
Level of measurement of data; characterizes data that may be arranged in order but, differences between data values either can not be determined or are meaningless
Ogive
Graphical representation of a cummulative frequency distribution
Observation Study
study in which we observe and measure but don't attempt to manipulate or modify the subjects being studied
Mode
Value that occurs most frequently
Range
the measure of variation that is the difference between the highest and lowest values
Standard deviation
measure of variation; equal to the square root of varience
Frequency Polygon
Graphical representation of the distribution of data using connected straight lines
Discrete data
Data with the property that the number of possible value is either a finite number or a countable number
Data
Number or information describing some characteristic
Convenience
Sampling in which data is selected because it is readily available
Experiment
Application of some treatment followed by observation of it's effect on the subjects
Histogram
Vertical bar graph representing the frequency distribution of a set of data
Quantitative data
data consisting of numbers representing counts or measurements
Qualitative data
Data that can be separated into different categories distinguished by some nonnumerica characteristic
P value
probability that a test statistic in a hypothesis test is at least as extreme as the one actually obtained
Cluster
Dividing the population area into sections (or clusters) then randomly selecting a few of those sections. Then selecting all the members from those selected sections
Null hypothesis
claim made about some population characteristic; usually involving case of no difference;
Dependent Sample
Sample whose values are related to the values in another sample
Variance
measure of variation; equal to the square of the standard deviation
Relative frequency histogram
bar graph (histogram) in which frequencies are replaced by relative frequencies
Upper class limits
Largest number that can belong to the different classes in a frequency distribution
Continuity Correction
Adjustment made when a discrete random variable is being approximated by a continous random variable
Correlation
Statistical assocation between two variables
Test statistic
statistic based on the sample data; used in making decision about rejection of the null hypothesis
Systematic sampling
Sampling in which every "k"th element is selected
Stratified sampling
Sampling in which samples are drawn from each stratum(class)
Simple event
Experimental outcome that cannot be further broken down
Critical region
the set of values of the test statistic that would cause rejection of the null hypothesis
Critical value
Value separating the critical region from the values of the test statistic that would not lead to rejection of the null hypothesis
Confidence Level
Probability that a population paramenter is contained within a particular confidence interval
Voluntary response sample
Sample in which the respondents decide whether to be included
Range rule of thumb
Rule based on the principle that for typical data, the difference between the lowest value and the highest value is approx. 4 standard deviations.
Pareto Chart
bar graph for qualitative data with the bars arranged in order, according to frequency
Parameter
measured characteristic of a population
Significance level
Probability of making a type I error when conducting a hypothesis test
Event
Outcome of an experiment
Factorial Rule
N" different items can be arranged "N!" different ways
Fundamental counting rule
For a sequence of two events in which the 1st event can occur in "n" ways; the 2nd can occur in "m" ways; together they can occur in "m*n" ways
Interval level
level of measurement of data; data can be arranged in order and differences between data values are meaningful
Lower class limit
Smallest number that can belong to the different classes in a frequency distribution
measure of center
value intended to indicate the center value in a data set
Multimodial
having more than 2 modes
Nominal
level of measurement of data; data consisting of names, labels or categories
non sampling errors
errors from external factors not related to sampling
binomial probability distribution
discrete probability distribution of the number of sucesses
discrete random variable
random variable with either a fininte(whole) number value or a countable number.
arithmetic mean
the sum of a set of values divided by the number of values
Statistics
collection of methods for planning experiments, obtaining data, organizing, summarizing, presenting, analyzing, interpreting and drawing conclusions, based on data
Standard normal distribution
normal distribution with a mean of 0 and a standard deviation =1
Outlier
values that are very unusual; they are very far away from most of the data
median
Middle value of a set of values arranged in order of magnitude
Midrange
1/2 of the sum of the highest value + lowest value
Complement
outcomes in which the original event does not occur
disjoint
events that can NOT occur at the same time
class boundaries
values obtained from a frequency distribution by increasing the upper class limit and decreasing the lower class limit by the same amount, so there are NO GAPS between consecutive classes
Continuous data
data resulting from infinitely many possible values that correspond to some continous scale that covers a range of values without gaps.
Cumulative frequency
sum of the frequencies for a class and all preceding classes
Frequency distribution
listing of data values (either individually or by groups) along with their corresponding counts
Continuous random variables
random variable with infinite values that can be associated with points on a continuous line interval
Placebo effect
occurs when an untreated subject incorrectly believe that he/she is receiving a real treatment and reports improvement in symptoms
Population
complete and entire collection of elements to be studied
random sample
sample selected in a way that EVERY member of the population to have the same chance of being chosen
Characteristics of Data
Center, Variance, Distribution, Outliers, changing over Time
Sampling error
difference between a sample result and the true population result; caused by chance sample fluctuations
scatter plot
Graphical display of paired (x,y) data
Random variable
variable (usually x) that has a single numerical value(determined by chance) for each outcome of an experiment
Confidence Interval
range of values used to estimate some population parameter with specific level
confidence interval limits
2 numbers that are used as the high & low boundaries of a confidence interval
sample size
number of items in a sample
ratio level
level of measurement of data; can be arranged in order; differences are meaningful; there is an inherent zero starting point
relative frequency distribution
basic frequency distribution in which the frequency for each class is divided by the total of all frequencies
sample
subset of a population
sample space
all possible outcomes(events) in an experiment that cannot be further broken down
Point Estimate
single value that serves as an estimate of a population parameter
standard score
number of standard deviations that a given value is above or below the mean; also called z-score