# psyc 271 Stats powerpoint terms

37 cards

psyc 271

Created Sep 27, 2011
by
cjbenassi

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 Side A Side B 1 real limits of a number •midway point between the number & the next lower and next higher number on the scale 2 frequency distributions •Table that orders scores from highest to lowest.  Also tells you how often each score... 3 simple bar graph used for qualitative variables 4 stem and leaf plots •Combo of frequency table and histogram •Uses 1s, 10s, 100s digits to sort and group 5 positively skewed distribution •if the TAIL, NOT THE SCORES, occur at high end 6 negatively skewed distribution •if the TAIL, NOT THE SCORES, occur at low end 7 measures of central tendency •Descriptive statistics providing a brief summary of the center point of a distribution 8 mode •Not as sensitive as the mean to changes in all scores of distribution •It is possible... 9 median •Less sensitive than mean to changes in value of scores or to extreme values •Best measure... 10 mean •This is the most sensitive measure of central tendency •A change in one score changes... 11 variability •Descriptive statistics that summarize the amount of the differences between scores...can... 12 range •Insensitive!  Based on only 2 scores •Subject to bias of outlying or extreme... 13 interquartile range (IQR( •The range of values for the middle 50% of the scores in a distribution •IQR = X75... 14 semi-interquartile range (SIQR) •Equal to ½ of the IQR •Indicates the number of scale units around the median that... 15 variance •Four important properties –1. Sensitive – every score is used in its computation –2. Logical... 16 standard deviation •tells us the approximate average deviation from the mean 17 normal distribution •A theoretical or mathematically ideal distribution •It can be used to estimate relative... 18 parameters •Statistics that measure all members of a population –Mean = μ (meu) –Standard Deviation... 19 properties of normal distribution 1.Symmetrical 2.Scores cluster around the vertical axis 3.Asymptotic (approaches the... 20 standard normal distribution •A normal distribution on which all values on the X-axis are expressed as z scores 21 relative frequency distribution •The area underneath the curve is the relative frequency distribution!....maximum value... 22 cumulative relative frequency distribution Area under curve 23 probability subjective and empirical...# of occurences/ total # of possible events...from 0 to 1 or from... 24 standard score •Provides logical and objective way to combine scores from different distributions •Provides common... 25 ratio scale A scale of measurement that has a true zero point and on which numbers are assigned to correspond... 26 interval scale A scale of measurement that does not have a true zero point, but on which numbers are assigned... 27 nominal scale A scale of measurement on which numbers are assigned to objects but the objects have only... 28 ordinal scale A scale of measurement on which numbers are assigned to objects, but the objects have only... 29 The standard deviation of a distribution of sample means is Called the standard error of the mean .... 30 inference reasoning from something known to unknown 31 statistical inference drawing conclusions about population parameters from sample statistics 32 point estimation estimating the value of the parameter as a single point from the value of a statisticlProvides... 33 unbiased estimator lThe average of estimates from an infinite number of random samples would equal the population... 34 consistent estimator lIs one, that as the sample size increases, the probability that the estimate has a value... 35 stratified random sampling lA stratum is a layer or level of some characteristic of a population. lDefine ahead of... 36 central limit theorum lIf we take an infinite number of samples (of size N) from any population containing an infinite... 37 interval estimation lProvides an estimated range for μ lUses X as a base lSx and sampling distribution lProbability concepts lConfidence intervals...