Vocab
a distribution showing the frequency at or below each category
cumulative frequency distribution
the hypothesis stating what the researcher is seeking evidence of. A statement of inequality. It can be written looking for the difference or change in one direction from the null hypothesis or both.
alternative hypothesis
how do you check if their are outliers
calculate IQR; anything above Q3+1.5(IQR) or below Q1-1.5(IQR) is an outlier
characteristics of Normal curve
symmetric, single peaked, bell shaped
a formal procedure for using observed data to decide between 2 competing claims (hypothesis)
significance test
a distribution showing the percentage at or below each category
cumulative percentage distribution
The minumum value, lower quartile, median, upper quartile, and maximum value for a data set. These five values give a summary of the shape of the distribution and are used to make box plots.
five number summary
Relationship between variance and standard deviation?
variance=(standard deviation)^2
where is the mean location on Normal curve
center of the curve
a statement of "no difference"
null hypothesis
a table reporting the number of each observations falling into each category of the variable
frequency distribution
a measure of how many standard deviations you are away from the norm (average or mean)
z score
What should we use to measure spread if the median was calculated?
iqr
where is standard deviation on Normal curve
distance from center to change of curve points
The probability, computed assuming H0 s true, that the statistic would take value as extreme as or more extreme than the one actually observed in the direction specified by Ha.
p value
an equation stating that two ratios are equal
proportion
(statistics) the entire aggregation of items from which samples can be drawn
population
What is the IQR? How much of the data does it represent?
Q3-Q1; 50%
area represents the _ of a distribution
percentile
Dental associations recommend that the time lapse between routine dental checkups should average 6 months. A random sample of 36 patient records at one dental clinic showed the average time between checkups to be 9.2 months with standard deviation of 2 months. Does this indicate that patients wait longer than the recommended 6 months between checkups? Test at 1%.
Hypothesis: H0: π = 6 and Ha: π > 6 Conditions: Random: SRS and there are at least 10(36) = 360 patients Normal: Since n β₯ 30, the Central Limit Theorem ensures that the distribution is approximately normally distributed Mechanics: t = 9.2β6 2 β36 β = 9.6, df = 35 and p = 1.22 x 10-11 Conclusion: Since p = 1.22 x 10-11 < 0.01, we reject the null hypothesis and conclude that there is enough evidence to state that patients wait longer than the recommended 6 months between checkups.
a ratio that compares 2 quantities
rate
data that can be placed in categories
categorical data
If a possible outlier is on the fence, is it an outlier?
no
The variance for the binomial probability distribution is
var(x) = nP(1-P)
A company claims that the mean weight per apple they ship is 120 grams. Data generated from a sample of 49 apples randomly selected from a shipment indicated a mean weight of 118.5 grams per apple with a standard deviation of 12 grams. Is there evidence to reject the companyβs claim? (test at 5%)
Hypothesis: H0: π = 120 and Ha: π β 120 Conditions: Random: SRS and there are at least 10(49) = 490 apples in a shipment Normal: Since n β₯ 30, the Central Limit Theorem ensures that the distribution is approximately normally distributed Mechanics: t = 118.5β120 12 β49 β = -0.875, df = 48 and p = 0.193 x 2 = 0.3859 Conclusion: Since p = 0.3859 > 0.05, we fail to reject the null hypothesis and conclude that there is not enough evidence to state that the mean weight per apple is different from 120 grams. _______________________________________