UNDERSTANDING STATISTICS

Wide bell curve?

-Large SD -More variability

Ratio

-difference can be quantitatively measured -absolute zero

Interval

-difference can be quantitatively measured -no absolute zero

Nominal

-naming level -participants will respond with words not numbers

Ordinal

-ordering from high to low -does not measure amount of variation between -can be quantified

Univariate Analysis

Analyzing how participants vary on only one variable

Bivariate Analysis

Analyzing the relationship between two nominal variables

Median score has ____% above and below

50%

In a normal distribution, _____ percent of the participants in the distribution lie within one SD off the mean

68%

Why do we use null hypoth?

Hypothesis: the loss of my socks is due to alien burglary. However, when you get your results, it's possible that any relationship that appears in your data was produced by random chance. In order to back up your hypothesis you need to compare the results against the opposite situation: that the loss of socks is not due to alien burglary. This is your null hypothesis - the assertion that the things you were testing (i.e. rates of alien activity and sock loss) are not related and your results are the product of random chance events.

Which is more reliable statistic? Range or IQR?

IQR

Objective, multiple choice achievement tests are usually used to measure at what level?

Interval

Weight measured in points uses what scale of measurement?

Interval

SD size of short and wide bell curve?

Large

Which group has less variability? Group with SD of 14 or group with SD of 20

SD of 14

Use mean or median ordinal measurement?

Median

IQR

Middle two quarters, or middle 50% of the participants

Bell Curve: Skewed to the right

Positive Skew

Measure of variability used when the MEAN measure of central tendency

Standard deviation

How do we determine the probability that the null hypothesis is true? (and consequently that our results are not)

Significant tests

T/F: If researchers do not sample, they do need inferential statistics

True Why? Because without a sample, it is sure that the study population is free of "sampling errors"

T/F: Null hypothesis can never be proven

True! Researcher can only reject or failed to reject based on probability of truth

When all values are the same, what is the SD?

zero

Frequencies and statistics are used with what branch of statistics?

descriptive

Null hypoth more likely to be stated in journal article or dissertation?

dissertation

Direct relationship

high on one variable are high on another

Inverse relationship

high on one variable are low on another

Do researchers reject null hypothesis when the probability of its truth is high or low?

low

Inferential Statistics

make inferences from samples to the entire populations from which the samples were drawn

Margin of error is used with what branch of statistic?

margin of error

Known as the balance point in a distribution

mean

Synonym for averages

measures of central tendencies

Used when distribution is highly skewed?

median

Most frequently occurring score

mode

Which of the three averages is seldom used in formal reports of research?

mode

Which scale of measurement is the lowest?

nominal

Which are harder to comprehend: proportions or percentages?

proportions

Does the term sampling error refer to random errors or bias?

random errors

Values obtained from a sample?

statistics

Descriptive Statistics

summarize and describe data

Alternative way to saying a researcher has rejected the null hypothesis?

the difference (of your research results) is statistically significant

Measure of variability used when the MEDIAN measure of central tendency

Range/IQR

Number of minutes of overtime work uses what scale of measurement?

Ratio

What does the null hypothesis say about sampling error?

The observed difference in results was created by random errors

T/F: The 68% rule of thumb does not strictly apply if the distribution is not normal

True

Which branch helps researchers to make generalizations about the characteristics of populations on the basis of data obtained by studying samples

inferential

Which branch of statistics helps researchers to draw inferences about the effects of sampling errors on their results described with descriptive statistics

inferential

Values obtained from a population?

parameters

Significance tests--which branch of statistics?

*inferential statistic helps researchers to decide whether the differences in descriptive statistics are reliable

Narrow bell curve?

-Small SD -Less variability

IQR 1,1,1,2,3,4,5,6,7,8,8,9,10,11,11,12

1,1,1,2 3,4,5,6 7,8,8,9 10,11,11,12 2.5--6.5--9.5 9.5-2.5=7

Three rationale of null hypothesis?

1. Observed difference was created by sampling error 2. No true difference between the two groups 3. True difference is zero

Why is range an unreliable statistic?

Based on two most extreme scores

Bell Curve: Skewed to the left

Negative Skew

SD size of tall and narrow bell curve?

Small

Use standard deviation to describe the....

variability *different groups can have same mean, but very difficult SD--variability between participants