Statistics Test #1 - Spring 2013

The __ is typically used to describe skewed distributions of data and measures on an ordinal scale

Median

The middle score in the data set that is listed in numerical order, where half of all scores fall above and half fall below its value.

Median aka 50th percentile - not the average, point on distribution where half scores are above and half scores are below

A set of individuals, items, or data taken from a population of interest (representative subset of a population)

Sample Data are termed "statistics"

A distribution of all sample means or sample variances that could be obtained in samples of a given size from the same population

Sampling Distribution

Rules for how the properties of numbers can change with different uses

Scales of Measurement They are characterized by 3 properties: order, differences, and ratio

______ is the study of phenomena through strict observation, evaluation, interoperation, and theoretical explanation

Science

The empirical rule

States that for any normally distributed set of data, at least 99.7% of data lie within 3 standard deviations of the mean, at least 95% of data lie within 2 SD of the mean, and at least 68% of data lie within one SD of the mean

A branch of mathematics used to summarize, analyze, and interpret what we observe - to make sense or meaning of our observation

Statistics

____ are measures used to divided data into tow more parts

factiles

A study that lacks randomization, manipulation, or comparison is called a _________ experiment

quasi-experimental: This most often occurs in one of two ways: The study includes a quasi-independent variable The study lacks a comparison group pg. 9

Measures of variability include the _____, ____, & _______

range, variance, and SD

Nominal - Category [MODE] Ordinal - Order (class rank/grades) [MODE/MEDIAN] Interval - Equal distances between points, more precise than being ordered (temperature/time) [MODE/MEAN] Ratio- Absolute Zero [MODE/MEAN]

...

The types of data researchers measures fall into two categories:

1. continuos or discrete 2. quantitative or qualitative look at pg. 19

State whether each of the following describe an experiment, quasi-experiment, or correlational method A. A researcher tests whether dosage level of some drug (low, high) causes significant differences in health B. A researcher tests which political affiliation (Republican, Democrat) is associated with different attitudes toward morality. C. A researcher measures the relationship between income and life satisfaction.

A. Experiment B.Quasi - Experimental C.Correlational method

Why is variance a preferred measure of variability?

Because it includes all scores in its computation

Measures of ___ _______ are statistical measures for locating a single score that is most representative or descriptive of all scores in a distribution. 3 measures of Central Tendency:

Central Tendency mean median mode

Two outcomes are ______ when the sum of their probabilities is equal to 1.0

Complementary

Two outcomes are _______ when the probability of one outcome is dependent on the occurrence of the other

Conditional

A ______ variable is measured along a continuum, whereas as ______Variable is measured in whole units or categories.

Continuous Variable Discrete Variable (Hence, continuous but not discrete variables are measured at any place beyond the decimal point)

What the two types of data that are collected and measured quantitatively?

Continuous and discrete numbers

_______ describes a set of measurements (made up of raw scores) A ______ ______ describes individual measurements

Data Raw score

The measured in an experiment is referred to as the ______ variable Dependent variables can often be measured in many ways, and therefore require an ______ ________

Dependent "presumed effect" operational definition: a description of some observable event in terms of the specific process or manner by which it was observed or measured

______ are techniques used to summarize or describe numeric data

Descriptive Statistics

Two general types of statistics/branches

Descriptive: Summarize or organize scores Inferential: Allows sample results to be generalized to representative populations (Used to interpret the meaning of descriptive statistics)

Limitations of Median:

Doesn't describe everyone/everything in the data set; can have a bias perspective Median doesn't take into account extreme scores Median only takes into account one or two scores at best

T/F Inferential statistics are used to help the researcher infer whether observations made with samples are reflective of the population.

TRUE

Population A characteristic that describes a population is referred to as a _____ ________

Entire set of individuals or items of interest (set of all individuals, items, or data of interest) Ex.everyone enrolled in REF 602 Data are termed "parameters"

3 research methods commonly used in behavioral science:

Experimental design uses randomization, manipulation, and comparison to control variable to demonstrate cause-and effect relationships. Quasi-experimental design is structured similar to an experiment but lacks randomization. Correlational Method is used to measure pairs of scores for each individual and examine the relationship between the variables.

When the mean is greater than the mode, the distribution is positively skewed. T/F

TRUE

Two outcomes are _______ when the probability of one outcome does not affect the probability of the second outcome. follows what rule?

Independent Multiplicative Rule

The variable that is manipulated in an experiment. This variable remains unchanged (or independent) between conditions being observed in an experiment. ("presumed cause")

Independent Variable

Interval variable DO/DO NOT have a true zero and ratio variable DO/DO NOT have a true zero.

Interval variable DO NOT have a true zero Ratio variable DO have a true zero

8 characteristics of a normal distribution are:

Is mathematically defined Theoretical Mean, median, and mode are located at the 50% percentile Symmetrical THe mean can equal any value SD can equal any positive value Total area under the curve is equal to 1.00 The tails of a normal distribution are asymptotic

Sum of set of scores divided by the total number of scores summed

Mean

The value in a data set that occur most often or most frequently.

Mode * Can be used for all levels of scale* (nominal, ordinal, interval, ratio)

Pro of Mean

Takes into account all scores in the data

Which of the following is not an example of a ratio scale? Age (in days) Speed (In seconds) Height (in inches) Movie ratings (1 to 4 starts)

Movie ratings (1 to 4 stars)

____ scales are measurements where a number is assigned to represent someone or something

Nominal

Four scales of measurement:

Nominal: Are typically coded (seasons, months, gender) Ordinal: Indicate order alone (rankings, grade level) Interval: Have equidistant scales and no true zero (rating scale values, temperature) Ratio: Also equidistant but have a true zero (weight, height, calories)

________ describes how a population is characterized, whereas ________ describes the characteristics of samples.

Parameters Statistics

The frequency of times an outcome occurs divided by the total number of possible outcome.

Probability, varies between 0 and 1 and is never negative symbolized as (p)

Descriptive Statistics:

Procedures used to summarize, organize and make sense of a set of scores or observations. (procedures used to make sense of observations by summarizing them numerically) Descriptive statistics are typically presented graphically, in tabular form, or as summary statistics

A ________ varaible varies by amount, whereas ______ variable varies by class

Quantitative Qualitative

Which scale of measurement is the most informative?

Ratio

Scales of Measurement were proposed by who? (nominal, ordinal, interval, and ratio)

S.S. Stevens in 1946 - a Harvard Psychologist

T/F An experiment is the only method that can demonstrate cause and effect between variables

TRUE

Measures the average squared distance that scores deviate from their mean

Variance

Number assigned to observations according to rules, called "scores" or "raw scores" (measurements or observations that are typically numeric) A datum (singular) is a signle measurement or observation, usually referred to as a ____ or ____ _______

data score or raw score

Any study that demonstrates cause is called an _____ 3 requirements must be satisfied for a study to be regarded as an experiment:

experiment Randomization, manipulation, and comparison

The mean is a preferred descriptive statistic for 3 things:

for describing normal distributions for summarizing interval scale measures for summarizing ratio scale measures

Mean is typically used to describe _______ and _________ scale data that are normally distributed.

interval and ratio scale

When two outcomes are _________ _________, the outcomes cannot occur together What rule?

mutually exclusively Additive Rule

The ____ _______ is a theoretical distribution with data that symmetrically distributed around the mean, the median, and the mode

normal distribution

The mean for a set of scores in an entire population is called a ________ mean; the mean for a sample (or subset of scores from a population) is called the _______ mean Each mean is computed the same but with different notation used to identify the sample size (n) and population size (N)

population sample

The standard deviation is always ______, and it is used to describe _____ data

positive; quantitative

Most behavioral research done on _______ _______ summarize sample results ______ generalize to populations

samples Descriptive Statistics Inferential Statistics

What do nominal scales represent? Ordinal values convey _____ alone

something or someone ORDER alone

Interval scale does not have a true _____

zero (ex. temperature)